CA1204788A - Methane conversion - Google Patents
Methane conversionInfo
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- CA1204788A CA1204788A CA000435442A CA435442A CA1204788A CA 1204788 A CA1204788 A CA 1204788A CA 000435442 A CA000435442 A CA 000435442A CA 435442 A CA435442 A CA 435442A CA 1204788 A CA1204788 A CA 1204788A
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Abstract
ABSTRACT OF THE DISCLOSURE
A method for synthesizing hydrocarbons from a methane source which comprises contacting methane with an oxide of Mn, Sn, In, Ge, Pb, Sb, or Bi at a temperature of about 500 to 1000°C. The oxide is reduced by the contact and coproduct water is formed. A reducible oxide is regenerated by oxidizing the reduced composition with molecular oxygen. A preferred mode of operation comprises recirculating solids comprising the reducible oxides between two physically separate zones: a methane contact zone and an oxygen contact zone.
A method for synthesizing hydrocarbons from a methane source which comprises contacting methane with an oxide of Mn, Sn, In, Ge, Pb, Sb, or Bi at a temperature of about 500 to 1000°C. The oxide is reduced by the contact and coproduct water is formed. A reducible oxide is regenerated by oxidizing the reduced composition with molecular oxygen. A preferred mode of operation comprises recirculating solids comprising the reducible oxides between two physically separate zones: a methane contact zone and an oxygen contact zone.
Description
PF 50-55-OlllA
METHANE CONVERSION
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to synthesis of hydro-carbons from a methane source. A particular application of this invention is a method for converting natural gas to more readily transportable material.
ESCRIPTION OF THE PRIOR ART
A major source of methane is natural gas. Other sources of methane have been considered for fuel supply, e~g., the methane present in coal deposits or formed during mining operations. Relatively small amount of methane are also produced in various petroleum processes.
The composition of natural gas at the wellhead varies but the major hydrocarbon present is methane. For example the methane content of natural gas may vary within the range of from about 40 to 95 vol. ~. Other constitu-ents of natural gas may include ethane, propane, butanes,pentane (and heavier hydrocarbons)~ hydrogen sulfide, carbon dioxide, helium and nitrogen.
Natural gas is classified as dry or wet depending upon the amount of condensable hydrocarbons contained in it.
Condensable hydrocarbons generally comprise C3-~ hydrocarbons although some ethane may be included. Gas conditioning is ~2~
required to alter the composition of wellhead gas, process-ing facilities usually being located in or near the produc-tion fields. Conventional processing of wellhead natural gas yields processed natural gas containing at least a major amount of methane.
Large-scale use of natural gas often requires a sophisticated and extensive pipeline system. Liquefaction has also been employed as a transportation means, but processes for liquefying, transporting, and revaporizing natual gas are complex, energy-intensive, and require extensive safety precautions. Transport of natural gas has been a continuing problem in the exploitation of natural gas resources. It would be extremely valuable to be able to con~ert methane (e.g., natural gas) to more easily handleable, or transportable, products. Moreover, direct conversion to olefins such as ethylene or propylene would be extremely valuable to the chemical industry.
In addition to its use as fuel~ methane is used for the production of halogenated products (e.g., methyl chloride, methylene chloride, chloroform and carbon tetra-chloride). Methane has also been used as a feedstock for producing acetylene by electric-arc or partial-oxidation processes. Electric-arc processes are operated commer-cially in Europe. In partial-oxidation processes, a feed mixture of oxygen and methane (the methane may contain other, additional hydrocarbons) are preheated to about 540C and ignited in a burner. Representative processes of this type are disclosed in U.5. Patent NOs. 2,679,544;
METHANE CONVERSION
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to synthesis of hydro-carbons from a methane source. A particular application of this invention is a method for converting natural gas to more readily transportable material.
ESCRIPTION OF THE PRIOR ART
A major source of methane is natural gas. Other sources of methane have been considered for fuel supply, e~g., the methane present in coal deposits or formed during mining operations. Relatively small amount of methane are also produced in various petroleum processes.
The composition of natural gas at the wellhead varies but the major hydrocarbon present is methane. For example the methane content of natural gas may vary within the range of from about 40 to 95 vol. ~. Other constitu-ents of natural gas may include ethane, propane, butanes,pentane (and heavier hydrocarbons)~ hydrogen sulfide, carbon dioxide, helium and nitrogen.
Natural gas is classified as dry or wet depending upon the amount of condensable hydrocarbons contained in it.
Condensable hydrocarbons generally comprise C3-~ hydrocarbons although some ethane may be included. Gas conditioning is ~2~
required to alter the composition of wellhead gas, process-ing facilities usually being located in or near the produc-tion fields. Conventional processing of wellhead natural gas yields processed natural gas containing at least a major amount of methane.
Large-scale use of natural gas often requires a sophisticated and extensive pipeline system. Liquefaction has also been employed as a transportation means, but processes for liquefying, transporting, and revaporizing natual gas are complex, energy-intensive, and require extensive safety precautions. Transport of natural gas has been a continuing problem in the exploitation of natural gas resources. It would be extremely valuable to be able to con~ert methane (e.g., natural gas) to more easily handleable, or transportable, products. Moreover, direct conversion to olefins such as ethylene or propylene would be extremely valuable to the chemical industry.
In addition to its use as fuel~ methane is used for the production of halogenated products (e.g., methyl chloride, methylene chloride, chloroform and carbon tetra-chloride). Methane has also been used as a feedstock for producing acetylene by electric-arc or partial-oxidation processes. Electric-arc processes are operated commer-cially in Europe. In partial-oxidation processes, a feed mixture of oxygen and methane (the methane may contain other, additional hydrocarbons) are preheated to about 540C and ignited in a burner. Representative processes of this type are disclosed in U.5. Patent NOs. 2,679,544;
2,234,300; and 3,244,765. Partial oxidation produces significant quantities of CO, CO2 and H2, yielding a diulte 20~7~8 :
` :
acetylene-containing gas and thereby making acetylene recovery difficult.
The largest, non-fuel use of methane is in the production of ammonia and methanol ~and formaldehyde)~ The first; methane conversion, step of these processes is the production of a synthesis gas ~CO + H2) by reforming of methane in the presence of steam overr for example, a nlckel catalyst. Typlcal reformers are tubular furnances ; heated with natural gas, the temperature being maintained at 900C and the pressure at about 225 atmospheresO
Pyrolytic or dehydrogenataive conversion of methane or natural gas to C2+ hydrocarbons has previously ` been proposed. The conversion required high temperatures `~ (greater than about 1000C.) and is characterized by the ,~ formation of by~product hydrogen. ~he patent literature contains a number of proposals to catalyze pyrolytic l reactions, allowing conversion at lower temperatures. See, 1~ for example, U.S. Patent Nos. 1,656l813; 1,687,890;
~` 1,851,726 1,863,212; 1,922,960; 1~958,648; 1,986,238 and 1,988,873. U.S. Patent 2,436,595 discloses and claims a : `
catalytic, dehydrogenative methane-conversion process which employs fluidized beds of heterogeneous catalysts comprising an oxide or other compound of the metals of group VI or VIII.
Including oxygen in a methane feed for conversion over metal oxide catalysts has been proposed. Margolis, L.
Ya., Adv. Catal. 14/ 429 (1963) and Andtushkevich, T.V., et al, Kinet. Katal 6, 860 (1965) studied oxygen-methane cofeed over different metal oxides. ~hey report the forma-tion of methanol, formaldehyde, carbon monoxide and carbon ~2~
dioxide from methane/oxygen feeds. Higher hydrocarbons are either not formed or are converted much faster then methane.
Fatiadi has prepared an extensive review of reactions in which manganese dioxide is used for mild, selective heterogeneous oxidation of numerous classes of organic compounds. The us~ of manganese dioxide to form higher hydrocarbon products from methane is not mentioned.
Fatiadi, A. J., "Active Manganese Dioxide In organic Chemistry - Part I", Synthesis, 1976, ~o. 2, pp. 65, et seq.
(February, 1975); Fatiadi, A. J., "Active Manganese Dioxide In Organic Chemistry - Part II", Synthesis, 1976, No. 3, pp. 113, et seq. (March, 1976).
It has been reported that manganese oxide forms manganese carbides from methane at 800~. Fisher, F., et al, Brenstoff - Chem., 10, 261 (1929).
SUMM~RY OF THE INVENTION
It has been found that methane may be converted to higher hydrocarbon products by contactiny a methane-containing gas with oxides of manganese, tin, indium, germanium, lead, antimony and/or bismuth at temperatures selected within the range of about 500 to 1000C. Hydro-carbons produced include lower alkanes, lower olefins and aromatics. The oxides are reduced by the methane contact and are easily reoxidizable by contact with an oxygen-containing gas.
The present process is distinguished from previously known pyrolytic methane conversion processes by the use of the aforementioned reducible oxides to synthe-size higher hydrocarbons from methane with coproduction of water, rather than methane.
The present process is distinguished from previously suggested methane conversion processes which rely primarily on interactions between methane and at least one of nickel and the noble metals, such as rhodium, palladium, silver, osimum, iridium, platinum and gold. An example of this type of process is disclosed in U.S. Patent ~,205,194. The present process does not require that methane be contacted with one or more of nickel and such noble metals and compounds thereof.
Moreover, in a preferred embodiment, such contac-ting is carried out in the substantial absence of catalyt-ically effective nickel and the noble metals and compounds thereof to minimize the deleterious catalytic effects of such metals and compounds thereof. For example, at the conditions, e.g., temperatures, useful for the contacting step of the present invention, these metals when contacted with methane tend to promote coke formation, and the metal oxides when contacted with methane tend to promote forma-tion of combustion products (COx) rather than the desired hydrocarbons. The term "catalytically effective" is used herein to identify that qua~tity of one or more of nickel and the noble metals and compounds thereof which when present substantially changes the distribution of products obtained in the contacting step of this invention relative to such contacting in the absence of such metals and compounds thereof.
Oxides of manganese which are reduced when contacted with methane at a temperature of about 500-1000C.
include MnO2, Mn2O3, Mn3O4 or mixtures thereof. However, it has been further discovered that, of these reducible oxides of manganese, Mn3O4 is the most effective in promot-ing high yields of hydrocarbon products. The spinel, Mn3O4, is known to be formed by oxidation/decomposition of manganese compounds at temperatures above about 900C. and can be stabilized at lower temperatures, e.g., by being supported on silica.
A preferred oxide of tin is SnO2.
A preferred oxide of indium is In2O3.
A preferred oxide of germanium is GeO2.
A preferred o~ide Gf lead is PbO.
A preferred oxide of antimony is Sb2O3.
A preferred oxide of bismuth is Bi2O3.
It has been further found that use of elevated pressures (i.e., pressures greater than atmospheric) in the methane contact zone of processes employing one or more of the aforementioned reducible oxides promotes the formation of C3+ hydrocabon products (i.e., hydrocarbons having three or more carbon atoms per molecule). According to this distinct embodiment of the present invention, methane contact zone pressures are preferably within the range of about 2 to 100 atmospheres, more preferably within the range of about 3 to 30 atmospheres.
The conversion of methane to higher hydrocarbons by contact with oxidative synthesizing agents involves multiple reactions which are not clearly understood.
However, gas-(or vapor-) phase reaction products may be generally characterized as: (1) hydrocarbon products and (2) combustion products. Hydrocarbon products include al~anes, olefins and aromatics. The process is distin-guished from pyrolytic methane conversion processes by the coproduction of water, rather than hydrogen, and by the competing combustion reactions occurring during methane contacting.
A further distinct embodiment of the presently claimed invention resides in the discovery that improved results (e.g., production of hydrocarbon products while reducing the formation of combustion products during methane-contacting) are obtained by employing a process wherein solids (i.e., solid particles) are recirculated between two physically separate zones: a methane contact zone and an oxygen contact zone~ Desirable product distri-butions may advantageously be obtained if particles compri-sing an oxidative synthesizing agent and a gas comprising methane are continuously introduced (e.g., at independently chosen feed rates) into the methane contact zone, which zone is maintained at selected contact temperatures.
Moreover, maintaining fluidized beds o solids in the two contact zones enables control of average solids residence time in each zone and promotes mixing of the two-phase mixtures present in the zones. Average residence time of the methane-containing feed is also controlled. This mode of operation further improves product composition and reduces the formation of combustion products in the methane contact zone, especially when compared to cyclic processes involving intermittent or pulsed flow of methane and oxygen over solids maintained in a single contact zone or when ~2~4~
compared to processes wherein oxygen and methane are cofed over metal oxide catalysts.
Moreover, the process of the present invention provides the capability of producing a substantially uniEorm stream of desirable hydrocarbon products from relatively easily combustible material--methane--while employing oxidative synthesizing agents which are reduced during the methane-contacting. Such substantially uniform hydrocarbon product streams result in, for example, more effective and easier separation of products.
This invention is further described in the following detailed description of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a plot of methane conversion and hydrocarbon product selectivity vs. time for the results reported in Example 3.
Figure 2 is a plot o methane conversion vs. time for the results reported in Examples 2 and 5.
Figure 3 is a plot of ~ C converted and hydro-carbon product selectivity vs. run time for the results reported in Example 10.
Figure 4 is a plot of ~ C converted and hydro-carbon product selectivity vs. run time Eor the results reported in Example 11.
Figure 5 is a plot of methane conversion and hydrocarbon product selectivity vs. time for the results reported in Example 13.
Figure is 6 a plot of methane conversion vs. time for the results reported in Example 13 and 14.
Figure 7 is a plot of methane conversion and 12~9~7~38 hydrocarbon product selectivity vs. time for the results reported in Examples 16 and 17.
Figure 8 is a plot of methane conversion and hydrocarbon product selectivity vs. time for the results reported in Example 18.
Figure is 9 a plot of methane conversion and hydrocarbon product selectivity vs. time for the results reported in Examples 19.
Figure 10 is a plot of methane conversion to gaseous products and C2+ hydrocarbon product selectivity vs. time for the combined results of Examples 20 and 21.
Figure is 11 a plot of methane conversion to gaseous products and ~2+ hydrocarbon product selectivity vs. run time for the results of Example 22.
Figure 12 is a plot of methane conversion and hydrocarbon selectivity vs. time for the results of Examples 23 and 24.
Figure 13 is a plot of methane conversion and hydrocarbon product selectivity vs. time for the results of Example 25.
Fi~ure 14 is a plot of methane conversion and hydrocarbon product selectivity vs. time ~or the results reported in Example 26.
Figure 15 is a plot of methane conversion and hydrocarbon product selectivity vs. run time for the results of Example 27.
~ igure 16 is a plot of methane conversion vs.
time for the results reported in Examples 22 and 28.
Fi~ure 17 is a plot of methane conversion and hydrocarbon product selectivity vs. time for the results of Example 30.
_ ~ _ ~2a~
Figure 18 is a plot of methane conversion vs.
time for the results of Examples 30 and 31.
Figure 19 is a plot of the ratio, ~ yield of C
hydrocarbon products/% yield of C2+ hydrocarbon products, vs. run time for the instantaneous results obtained in Examples 33 and 34 and Comparative Example A.
DETAILED DESCRIPTION OF THE INVENTION
_ Oxidative synthesizing agents are compositions comprising at least one oxide of at least one metal, which composition r when contacted with methane at a temperature selected within the range of about 500 to 1000C, produces C2+ hydrocarbon products, coproduct water, and a composi-tion comprising a reduced metal oxide. The composition of the oxidative synthesizing agent thus contains at least one reducible oxide of at least one metal. The term "reducible"
is used to identify those oxides of metals which are r~duced by contact with methane at tempera~ures selected within the range of about 500 to 1000C. The term "oxide(s) of metal(s)" includes: (1) one or more metal oxides (i.e., compounds described by the general formula MxOy wherein M
is a metal and the subscripts x and y designate the relative atomic proportions of metal and oxygen in the compound) and/or (2) one or more oxygen containing metal compounds, provided that such oxides and compounds have the capability of performing to produce higher hydrocarbon products as set -forth herein. Preferred oxidative synthe-sizing agents comprise reducible oxides of metals selected from the group consisting of Mn, Sn, In, Ge, Pb, Sb, and Bi, and mixtures thereof. Particularly preferred oxidative synthesizing agents comprise a reducible oxide of manganese and mixtures of a reducible oxide of manganese with other oxidative synthesizing agents. More preferred are oxida-tive synthesizing agents which comprise Mn3O~. Among the reducible oxides of manganese, those containing major amounts of Mn2O3 and Mn3O4 are preferred~ As noted, a particularly preferred class of oxidative synthesizing agents are those comprising Mn3O4. Among the reducible oxides of tin, those containing major amounts of SnO2 are preferred. Among the reducible oxides of indium, those containing major amounts of In2O3 are preferred. Among the reducible oxides of germanium, those containing major amounts of GeO2 are preferred. Among the reducible oxides of lead, those containing major amounts of PbO are pre-ferred. Among the reducible oxides of antimony, those containing major amounts of Sb203 are preferred. Among the reducible oxides of bismuth, those containing major amounts of Bi2o3 are preerred.
Reducible oxides are preferably provided as particles. They may be supported by, or diluted with, a conventional support material such as silica, alumina, titania, zirconia, and the like, and combinations thereof.
A presently preferred support is silica.
Solids may be formed in conventional manner using techniques well known to persons skilled in the art. For example, supported solids may be prepared by conventional methods such as adsorption, impregnation, precipitation, coprecipitation, or dry-mixing.
A suitable method is to impregnate the support with solutions of a compound containing the metal. Some examples of metal compounds are the acetate, acetyl-~L2~
acetonate, oxide, carbide, carbonate, hydroxide, formate, oxalate, nitrate, phosphate, sulfate, sulfide, tartrate, fluoride, chloride, bromide or iodide. Such compounds may be dissolved in water or other solvent and the solutions combined with the support and then evaporated to dryness.
Preferably, aqueous solutions are employed and water-soluble compounds are usedO In some cases, the solutions may have acids and/or bases added to them to facilitate dissolution of the precursors of the metal oxide. For example, acids such as hydrochloric or nitric acid or bases such as ammonium hydroxide may be used as desired. The dried solids may then be screened or otherwise processed to form the desired shape, size, or other physical form of the finished solids. Finally, the solids are prepared for use by calcination at high temperatures for a period of time in accordance with conventional practice in this art. For example, the solids are placed in an oven or kiln, or in a tube through which oxygen (e.g., air or oxygen diluted with other gases) is passed, at an elevated temperature selected within the range of about 300 to 1200C. Particular calcin-ation temperature will vary depending upon the particular metal compound.
For solids comprising reducibl~ oxides of manganese, the calcination temperature should be within the range of about 500 to 1200C, preferably about 700 to 1200C, more preferably about 900 to 1200C. Use of higher calcination temperature promotes the formation of Mn3O4 in the finished solid.
For solids comprising reducible oxides tin, the calcination temperature should be within the range of about _ 12 -300 to 1200C, preferably about 500 to 1100C.
For solids comprising reducible oxides of indium, the calcination temperature should be within the range of about 300 to 900C, preferably about 500 to 850C.
For solids comprising reducible oxides of germanium, the calcination temperature should be within the range of about 300 to 1200C, preferably about 500 to 1000C.
For solids comprising reducible oxides of lead, the calcination temperature should be within the range of about 300 to 1000C, preferably about 500 to g00C. Use of higher calcination temperatures promotes the formation of PbO in the finished solid.
For solids comprising reducible oxides of antimony, the calcination temperature should be ~7ithin the range of about 300 ~o 1200~C, preferably about 500 to 850.
For solids comprising reducible oxides of bismuth, the calcination temperature should be within the range of about 300 to 1000~C, preferaby about 500 to 850C.
The foregoing description regarding preparation of reducible oxides of manganese, tin, indium, germanium, lead, antimony and bismuth in a form suitable for the synthesis of hydrocarbons from a methane source is merely illustrative of many possible preparative methods, although it is a particularly suitable method and is preferred.
Metal loadings on supported solids may be within the range of about 1 to 50 wt. % (calculated as the elemental metal(s) o the reducible oxides(s~.
In addition to methane, the feedstock employed in the method of this invention may contain other hydrocarbon ~ 13 -of nonhydrocarbon components, although the methane content should be within the range of about 40 to 100 vol. %, preferably from about ~0 to 100 vol. ~, more preferably from about 90 to 100 vol. ~.
Operating temperatures for the contacting of methane-containing gas and the oxidative synthesizing agent are selected from the range of about 500 to 1000C, the particular temperature selected depending upon the partic-ular oxide(s) employed in the oxidative synthesizing agent.
For example, all oxidative synthesizing agents have the capability of synthesizing higher hydrocarbons from a methane source when the temperature of the methane-contact are selected within the lower part of the recited range. Reducible oxides of certain metals, however, may require operating temperatures below the upper part of the recited range to minimize sublimation or volatilization of the metals (or compounds thereof) during methane contact.
Examples are: (1) reducible oxides of indium (operating temperatures ~7ill pr~ferably not exceed about 850C); (2) reducible oxides of germanium (operating temperatures will preferably not exceed about 800C); and (3) reducible oxides of bismuth (operating temperatures will preferably not exceed about 850C).
Operating temperatures for the contacting of methane-containing gas and a reducible oxide of manganese are in the range of about 500 to 1000C., preferably within the range of about 600 to 900C.
Operating temperatures for the contacting oE
methane-containing gas and a reducible oxide of tin are in the range of about 500 to 1000C., preferably within the range of about 600 to 900C.
Operating temperatures for the contacting of methane-containing gas and a reducible oxide of indium are in the range of about 500 to 850C., preferably within the range of about 600 to 800C.
Operating temperatures for the contacting of methane-containing gas and a reducible oxide of germanium are in the range of about 500 to 800C., preferably within the range of about 600 to 750C.
Operating temperatures for the contacting of methane-containing gas and a reducible oxide of lead are in the range of about 500 to 1000C., preferably within the range of about 600 to ~00C.
Operating temperatures for the contacting of methane-containing gas and a reducible oxide of antimony are in the range of about 500 to 1000C., preferably within the range of about 600 to 900C.
operating temperatures for the contacting of methane-containing gas and a reducible oxide of bismuth are in the range of about 500 to 850C., preferably within the range of about 600 to 800C.
Operating pressures for the methane contacting step are not critical to the broadly claimed invention.
However, both general system pressure and the partial pressure of methane have been found to effect overall results.
A distinct embodiment of the present invention is a method wherein an oxidative synthesizing agent comprising a reducible metal oxide is contacted with me-thane, the further improvement residing in the use of elevated pressures to promote the formation of C3+ hydrocarbon products. Operating pressures for the methane contacting step of this invention are preferably within the range of about 2-100 atmospheres, more preferably about 3-30 atmos-pheres. Elevated pressures have been found to provide improved results, e.g., elevated pressures promote forma-tion of C3+ hydrocarbon products.
Contacting methane and an oxidative synthesizing agent to form higher hydrocarbons from methane also reduces the oxidative synthesizing agent and produces coproduct water~ The exact nature of the reduced forms of oxidative synthesizing agents are unknown, and so are referred to herein as "reduced synthesizing agent" or as "a reduced metal oxide". Regeneration of a reducible oxide is readily accomplished by contacting reduced compositions with oxygen (e.g., an oxygen-containing gas such as air) a~ a tempera-ture selected within the range of about 300 to 1200C., the particular temperature selected depending on the particular metal(s) included in the oxidative synthesizing agent. The contact time should be sufficient to produce a reducible oxide from at least a portion of the reduced composition.
Oxygen contacting temperatures for reduced oxides of manganese are preferably within the range of about 300 to 1200C., more preferably within the range of about 700 to 1200C.~ still more preferably within the range of about 900 to 1200C. Higher reoxidation temperatures promote formation of Mn3O4, the preferred reducible oxide of manganese.
Oxygen contacting temperatures for reduced oxides of tin are preferably within the range of about 300 to ~L2~
1200C., more preferably within the range of about 500 to 1100C.
Oxygen contacting temperatures for reduced oxides of indium are preferably within the range of about 300 to 900C., more preferably within the range of about 500 to 850C. Higher reoxidation temperatures promote formation of In2O3, the preferred reducible oxide of indium.
Oxygen con~acting temperatures for reduced oxides of germanium are preferably within the range oE about 300 to 1200C., more preferably within the range of about 500 to 1000C.
Oxygen contacting temperatures for reduced oxides of lead are preferably within the range of about 300 to 1000C., more preferably within the range of about 500 to 900C. Higher reoxidation temperatures promote formation of PbO, the preferred reducible oxide of lead.
Oxygen contacting temperatures for reduced oxides of antimony are preferably within the range of about 300 to 1200C., more preferably within the range of about 500 to 850C~
Oxygen contacting temperatures for reduced oxides of bismuth are preferably within the range of about 300 to 1200C., more preferably within the range of about 500 to 850C.
Particles comprising a reducible oxide of Mn, Sn, In, Ge, Pb, Sb or Bi may be contacted with methane in fixed, moving, fluidized, ebullating, or entrained beds of solids.
Preferably, methane is contacted with a fluidized bed of particles comprising the said reducible oxides.
Similarly, particles comprising a reduced oxide of Mn, Sn, In, Ge, Pb, Sb~ or ~i may be contacted with oxygen in fixed, moving, fluidized, ebullating or entrained beds of solids. Preferably, oxygen is contacted with a fluidized bed of particles comprising the reduced oxides.
A single reactor apparatus containing a fixed bed of solids, for examplel may be used with intermittent or pulsed flow of a first gas comprising methane and a second gas comprising oxygen ~e.g., oxygen, oxygen diluted with an inert gas, or air, preferably air).
Preferably, however, the methane contacting step and the oxygen contacting step are performed in physically separate zones with particles recircula~ing between the two zones. Thus, the preferred method for synthesizing hydro-carbons from a methane source comprises: (a) contacting in a first zone a gas comprising methane and particles compri-sing an oxidative synthesizing agent to form higher hydro-carbon products, coproduct water, and reduced synthesizing agent; (b) removing particles comprising reduced synthe-sizing agent from the first zone and contacting the reduced particles in a second zone with an oxygen-containing gas to form particles comprising an oxidative synthesizing agent; and (c) returning the particles produced in the second zone to the first zone.
Particles comprising an oxidative synthesizing agent which are contacted with methane may be maintained as fluidized, ebullating, or entrained beds of solids. Prefer-ably, methane is contacted with a 1uidized bed of solids.
Similarly, partic~es comprising reduced synthes-izing agent which are contacted with oxygen may be main-tained as fluidized, ebullating or entrained beds of solids.
Preferably, oxygen is contacted with a fluidized bed of solids.
Thus, in a presently preferred embodiment of the present invention, methane feedstock and particles compri-sing an o~idative synthesiæing agent are continuously introduced into a methane contact zone maintained at synthesizing conditionsO Synthesizing conditions include the temperatures and pressures described above. The methane feedstock is introduced at sufficient velocity such that the particles are fluidized~ Gaseous reaction products from the methane contact zone (separated from any ~ntrained solids) are further processed--e.g., they are passed through a fractionating system wherein the desired hydrocarbon products are separated from unconverted methane and combustion products. Unconverted methane is preferably recovered and recycled to the methane contact zone.
Of considerable importance to the process of this invention is the average residence time of particles in the methane contact zone. Selection of a desired solids resi-dence time is dependent on the particular reducible metaloxide(s) incorporated in the particles comprising an oxida-tive synthesizing agent, the concentration of such active component, the feedrate and composition of the methane feedstock, and other operating conditions (esp. temperature and pressure of the contact zone). Preferably, the average residence time of particles in the fluidized bed contact zone is within the range of about 0.04 to 30 minutes, more preferably about 0.4 to 4 minutes. Optimum solids resi-dence times for any particular oxidative synthesizing agent will decrease as methane contact temperatures, gas eed ~20~
rates or hydrocarbon concentrations in the feed increase.
The feed rate of methane feedstock is related to the average residence time of particles, comprising an oxidative synthesizing agent, in the methane contact zone.
Preferably, residence time of methane feedstock in the methane contact zone is within the range of abou-t 0.1 to 100 seconds, more preferably about 1 to 20 seconds.
The SiZ2 of particles comprising an oxidative synthesizing agent is preferably selected to render those particles capable of fluidization, preferably in a dense phase, in the methane contact zone. These particle sizes are usual and are not peculiar to this invention.
Particles comprising reduced synthesizing agent are contacted with molecular oxygen in an oxygen contact zone for a time sufficient to restore or maintain the activity of the agent by oxidizing at least a portion of the reduced metal oxide to produce a reducible oxide and by removing, i.e., combusting, at least a portion of any carbonaceous deposit which may form on the particles in the methane contact zone. The conditions of the oxygen contact zone will preferably include a temperature selected within the range of about 300 to 1200C, pressures up to about 30 atmospheres, and average particle contact times within the range of about 3 to 120 minutes. Sufficient oxygen is preferably provided to oxidize all reduced metal oxide to produce a reducible oxide and to completely combust any carbonaceous deposit material deposited on the particles.
At least a portion of the particles comprising an oxidative synthesizing agent, which are produced in the oxygen 0 contact zone are returned to the methane contact zone.
- 20 ~
The rate of solids withdrawal from the methane contact zone is desirably balanced with the rate of solids passing from the oxygen contact zone to the methane contact zone so as to maintain a substantiall~ constant inventory of particles in the methane contact zone, thereby enabling steady state operation of the synthesis systemO
The invention is further illustrated by reference to the following examples.
Experimental results reported below include conversions and selectivities calculated on a molar basisO
Solids productivity, reported as g/g-hr., is grams of methane converted to C2~ hydrocarbon products/gram of solid oxidative synthesizing agent/hour.
The supported manganese oxides employed in Examples 1-11 were made by impregnating the appropriate amount of manganese, as manganeous acetate, onto the supports from water solutions. Supports used were Houdry ~SC 534 silica, Cab-O-Sil, Norton alpha-alumina and Davison gamma-alumina. The impregnated solids were dried at 110C for 4 hours and then calcined in air at 700C for 16 hours. Composition of the calcined solids is identified as "wt. % Mn/(support)".
Methane-contact runs described in Examples 1-11 were made at about atmospheric pressure in a quartz tube reactor (12 mm. inside diameter) packed with 10 ml~ of catalyst. The reactors were brought up to temperature under a flow of nitrogen which was switched to methane at the start of the run. Instantaneous samples of the effluent were taken throughout the run and analyzed by gas chromatography and gas chromatography- mass spectroscopy.
8~3 A cumulative run sample was also collected.
Examples 1-4 demonstrate the effect of manganese oxide loading on methane conversion. Total conversion is shown to bear a distinct relationship to loading.
A feed of 100% methane was passed over a bed of 5 wt. % Mn/SiO2 according to the procedure described above.
Contact zone temperature was 800C and the GHSV (gas hourly space velocity) was 600 hrs~l. Results are reported in Table I below. No carbon formation was detected on the solid present at the end of the run.
TABLE I
Time % _ % Selectivity (min) conv. CH2CH2 CH~CH~ C
Instantaneous Results 1 4.00 2~.5 37i4 1.991.8 19.9 21.0 2 1.02 17.6 59.8 1.47trace 14.3 4 .243 20.5 77.3 2.05 8 .166 22.2 74~6 3.0 .134 26.8 67.9 5.2 Cumulative Results 30 .429 27.2 45.~ 2.9 g.7 9.1 A feed of 100% methane was passed over a bed of 10 wt. % Mn/SiO2 according to the procedure described above.
Contact zone temperature was 800C and the GHSV was 600 hrs~l. Results are reported in Table II below. No carbon formation was detected on the solid present at the end of the run.
~2~7~
TABLE II
Run Time % % Selectivity (min) Conv. CH~CH2 CH3CH3 C~ C _ O~
Instantaneous Results * 1 Z2.4 40.7 18.2 2~1 17.1 18.9 4 .85 28.g 48.6 22.4 12 .32 3~.6 36.6 26.7 30 .27 56.7 43.2 Cumulative Results 1030 1.77 24.5 23~9 24O4 26.4 * Solids Productivity (Instantaneous) = 0.145 g/g hr.
A feed of 100~ methane was passed over a bed of 15 wt. % Mn/SiO2 according to the procedure described above.
Contact zone temperature was 800C and the GHSV was 600 hrs~l. Results are reported in Table III below. No carbon formation was detected on the solid present at -the end of the run. Figure 1 is a plot of % methane conversion and selectivity to C2+ hydrocarbon products vs. run time.
TABLE III
Run Time % % Selectivity (min) Conv. CH2CH2 CH~CH~ C~ C4-C7 CO CO~
Instantaneous Results -* 1 30.1 36.5 13.9 2.15 3.56 19.5 24.2 2 12.3 42.9 27.0 17.0 12.9 12 .402 55.8 44.1 30 .308 51.8 41.8 Cumulative Results 30 2.27 31.8 23.9 15.8 28.3 * Solids Productivity at 1 min = 0.157 g/g hr.
~7~
A feed of 100% methane was passed over a bed of 50 wt. % Mn/SiO2 according to the procedure described above.
Contact zone temperature was 700C and the GHSV was 600 hrs~l. Results are reported in Table IV below. No carbon formation was detected on the solids present at the end of the run.
TABLE IV
P~un Time % % Selectivity (min) Conv. CH~CH~ CH~CH~ c3 CO CO2 Instant~neous Results _ 1 22 D 8 2.3 3.46 .01 94.2 2 11.6 3.5 9.37 .05 .17 86.8 4 7.39 4.44 1~.8 .08 81O1 12 2.31 5.76 22.0 ~13 .~6 71.1 1.08 11.9 22.0 .36 65.6 Cumulative Results -30 4~12 4.26 12~5 .09 .36 82.6 This example demonstrates the recyclability of the Mn oxide, oxidative synthesizing agent of this inven-tion. The reduced solid remaining at the end of the run described in Example 2 was regenerated under a flow of air at B00C. for 30 minutes. The reactor was then flushed with nitrogen. The regenerated, reoxidized solids were then contacted with methane at a temperature of 800C and a GHSV of 600 hrs.~l. Results are shown in Table V below.
No carbon oxides were ~etected during the oxidation of the reduced solids. Comparison of the results reported in Tables II and V indicates substantially complete recovery of Mn oxide activity for the conversion of methane to higher hydrocarbons. Figure 2 is a plot of methane conver-sion vs. time for the combined results of Examples 2 and 5.
TABLE V
Run Time % % Selectivity (min) Conv. CH2(::H2 CH3CH3 ~ C0 Instantaneous Results 21.1 38.9 1705 2.4 18.8 lg.9 4 1.05 26.1 ds2~3 31.5 1012 .42 40.9 26.9 29.8 30 .36 64.8 35.2 Cumulative Results 30 1.56 25~2 18.1 1.3 24.7 30.7 The runs of this example show the effect of temperature on the conversion process of this invention. A
feed of 100% methane was passed over a bed of 5 wt. %
Mn/SiO2 at a GHSV of 600 hr. 1. Results obtained at various contact temperatures are shown in Table VI below.
TABLE VI
Run A
Time % % Selectivity TempC (min) conv. CH2CH2 CH3CH3, ~ C4-C6 C0 Instantaneous Results 650 2 1.25 2.4 19.1 trace 39.0 39.4 4 .28 503 62.1 27.5 16 .081 8~6 91.3 30 .03 15.8 84.1 Cumulative Results 3030 .223 6.7 52.0 21.5 19.7 Run ~
Time % % Selectivity TempC tmin) conv.CH2CH2 CH3CH3C3 C4-C~ CO C~2 Instantaneous Results 700 2 1.95 10.5 39.2 .9 23.0 26.1 4 .896 9.9 53.5 .08 27.5 8 .31 1370 87.1trace 16 .08713.7 86.2 .03 16.6 83.3 Cumulative Results 30 .319 14.1 67.1 9.4 9.
Run C
Temp~C (min) conv. CH2CH2 ~L3~ 5~ CO ~2_ Instantaneous Results 750 2 2.65 18.2 ~4.0 1.5 19.9 16.3 4 .5g6 15.1 81.0 1.3 2.5 8 .164 1~.6 85.3 16 .053 16O9 83.0 .041 17.0 ~3.0 Cumulative Results 30 .379 23.7 57.8 2.1 9.23 7.12 Example 1, supra, shows results of a similar run at 800C.
Initial and cumulative conversions increase with tempera-ture over the range of temperatures studied. Selectivities to higher, C3+, hydrocarbons tend to increase with tempera-ture as does the ratio of olefinic (e.g., ethylene) to paraffinic (e.g., ethane) hydrocarbon products. Formation of C3~ hydrocarbon products is promoted by higher tempera-tures.
~7~
Example 1 was repeated except that during prepar-ation of the supported Mn oxide, the dried impregnated catalyst was calcined in air at 1000C and the methane feed contained 16 vol. % methane, the remainder being N2.
Contact temperature was 750C and GHSV was 600 hrs.-l.
Results are shown in Table VII below. X-ray diffraction analysis of the calcined solid indicated that Mn was present as Mn3O4.
TABLE VII
Run Time % % Selectivity (min) Conv. CH2CH2 CH3CH3 ~_ CO C02 Instantaneous Results 1 12.7 - 15.7 17.5 .39 19.0 47.3 2 10.1 18.7 27.9 .49 21.6 31.1 4 2.59 19.7 47.7 ~77 16.5 15.26 12 1.02 12.3 49.1 .48 38.1 .289 32.8 65.4 1.73 Cumulative Results 30 2.96 17.4 13.7 .23 24.3 44.28 Example 3 This example demonstrates the effect of space velocity on the methane conversion process of this inven-tion. The procedure of Example 2 was repeated in the two Runs described in Table VIII below except that the space velocity of Run A was 1200 hrs -1 and space velocity of Run B was 300 hrs -1.
TABLE VIII
Run A
Run Time % % Selectivity (min) Conv. C2H4 ~2~h C3 C4-C7 CO CO~
Instantaneous Results -~5 5~25 22~2 ~0~3 ~15 27~0 8~8 1~0 o81 18~4 78~7 ~85 1~9 4~0 ~10 15~8 84~1 15.0 ~ 08 22 ~ 6 77 ~ 3 Cumulative Results -15 ~335 25~9 52~2 2~7 8~35 10~7 Run B
Run Time % % Selectivity (min) Conv. ~2~ C2H6 ~ C4-C7 CO ~2_ Instantaneous Results 1 37~ 20~1 4~6 1~20~7 48~1 25~3 2 l9.B 24.1 18.6 2.80~4 45~2 10~7 4 3~54 35~8 34~0 1~5~5 28~2 12 2~21 34~7 55~0 1~5 0 8 1.75 30 ~ 0 68 ~ 7 1.3 Cumulative Results _ 30 3~85 33~2 19~2 1~4 ~2 35~8 10~2 Example 9 Each of the following runs were made over 10 ml.
catalyst with a 14-16 vol. ~ CH4 in N2 feed. The feed rate (calculated at standard conditions) was 100 ml/min, equiva-lent to a GSHV Of 600 hrs~l. In Run A, the solid contact-ing agent was 5 wt. %Mn/gamma alumina and the contacting zone tempe-rature was 750C~ In Run B, the solid contacting 30 agent was 5 wt. % Mn/alpha-alumina and the contacting zone ~ 28 ~
7~
temperature was 750C. In Run C, the solid contacting agent was 5 wt. % Mn/SiO2 solids which had been subjected to at least 10 methane contact/oxidation cycles. In the oxidation portion of these cycles, reduced solids from the methane-contacting portion of the cycle were regenerated under a flow of air at 700C for 15 to 30 minutes and the reactor was then flushed with nitrogen before starting the next methane run. The contacting zone temperature for Run C was 700C. The results reported in Table IX are cumula-tive results obtained over a 30 minute contact time. X-ray diffraction analysis of the solid contacting agent used in Run C indicated that Mn was present as Mn3O
TABLE IX
Solids Productivity % ~ Selectivity x 103 Run# Conv. ~ C CO~2 (g/g-hr) A 6.12 11.4 .48 31.754.5 1.06 B 9.64 6.56 12.9 .07 80.3 0.95 C 1.23 12.0 51.6 .85 19.615.8 1.49 Example 10 A feed of 95 vol. % methane and 5 vol. % ethane was passed over a bed of 5 wt. ~ Mn/SiO2 according to the procedure described above. The contact temperature was 700C and the G~SV was 860 hrs~l. Unlike the runs described in the previous examples, a carbonaceous, coke-like deposit was present on the solids at the end of an 11 minute run. The results for the run, reported in Table X, below, are based on C in the feed converted to gas phase products only and do not take coke formation into account.
The amount of carbonaceous deposit formed over the 11 7~
minute run was 14.8% of all feed converted. Figure 3 is a plot of % C converted and % selectivity to C2+ hydrocarbon products vs. run time for the results of this example.
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7~8 Example 11 A feed of 95 vol. % methane and 5 vol. % ethylene was passed over a bed of 5 wt. % Mn/SiO2 according to the procedure described above. The contact temperature was 700C and the GHSV was 860 hrs~-l. A carbonaceous, coke-like deposit was present on the solids at the end of an 11 minute run. The amoun-t of carbonaceous deposit formed was 35.6% of all feed C converted. A wax-like condensate was also noted at the reactor outlet. The amount of this condensate was 5.0% of all feed C converted, Results for the run are tabulated in Table XI, Figure 4 is a plot of %
C converted and % selectivity to C2 + hydrocarbon products vs. run time for this example.
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The supported oxides of tin employed in Examples 12-15 were made by impregnation of tin ~artrate, in an aqueous solution of 7% hydrochloric acid, on Houdry HSC 534 silica, the amount of tin provided being sufficient to yield a solid containing 5 wt. % Sn/SiO2. The solids were dried at 110C for 4 hours and then calcined in air at 700C for 16 hours. The solids employed in the runs described in the examples are equilibrated solids, i.e., solids prepared as described above which have been contacted at least once with methane at a temperature of about 700C and then reoxidized by being contacted with air at about 700C.
Runs described in Examples 12-15 were made in a quartz tube reactor (12 mm. inside diameter) packed with 10 ml. of solids at about atmospheric pressure. The reactors were brought up to temperature under a flow of nitrogen which was switched to methane at ~he start of the run. Instantaneous samples of the effluent were taken throughout the runs and analyzed by gas chromatography and gas chromatography mass spectroscopy.
A feed of 100% methane was passed over a bed of solids as described ~bove. Contact zone temperature was 700C and the GHSV (gas hourly space velocity) was 600 hrs~l. Results are reported in Table XII below. No carbon was detected on the solid present at the end of the run.
~788 TABLE XI I
Run Time % % Selectivity ~min) conv. C2H4 ~ C~ C4-7 CO ~O~
Instantaneous Results .5 3.18 7.2 13.7.2 .8 15.5 62.3 1.0 1.27 8.8 17.2.5 2.7 24.7 45.7 2.0 .25 34,3 52.73.6 9.2 Cumulative Results -15 .23 29.9 29.93.4 8.6 11.0 16.9 A feed of 100% methane was passed over a bed of solids as described above. Contact zone temperature was 750C and the GHSV was 600 hrs~l. Results are reported in Table XIII below. No carbon was detected on the solid present at the end of the run. Figure 5 is a plot of %
methane conversion and % selectivity to C2 + hydrocarbon products vs. run time.
Run Time % % Selectivity (min~ conv. C~H~ fi C C4-7 CO ~2 20Instantaneous Results -.5 7.23 9.9 14.6 .4 .4 9.2 65.4 1.0 1.25 18.2 35.6 .7 1.0 2.3 42.2 2.0 .43 30.7 67.6 1.3 .2 Cumulative Results .
15 .54 24.7 40~8 .9 2.5 13.0 17.8 E_AMPLE 1 4 The reduced solid remaining at the end of the run described in Example 13 was regenerated under a flow of air at 750C for 30 minutes. The reactor was then flushed with nitrogen. The regenerated, reoxidized solids were then contacted with methane at a temperature of 750C and GHSV
of 600 hrsO~l. Resul-ts are shown in Table XIV below. No carbon oxides were detected during the oxidation of the reduced solids. Figure 6 is a plot of methane conversion vs. run time for the combined results of Examples 13 and 14.
TABLE XIV
Run Time % ~ Selectivity (min? _ conv. ~ C2H6 C3 C4-7 CO ~2 Instantaneous Results 10.5 6.52 11.2 1~.8.3 .2 13.5 59.8 1.0 1.10 22.7 34Ø5 .7 15.7 26.3 2.0 .37 32.7 65~21.2 .2 .8 Cumulative Results 15 .48 26.2 35.31.33.~ 12.0 21.9 The procedure of Example 12 was repeated except that contact zone temperature was 800C. Results are shown in Table XV below. No carbon was detected on the solid present at the end of the run.
TABLE XV
Run Time % ~ Selectivity (min? conv- ~2~ C2H6C~ C4-7 CO C02 Instantaneous P~esults .5 10.1 15.7 13.6.8 .9 11.1 57.7 1.0 3.2 26.7 21.11.71.8 18.2 30.3 2.0 2.2 20~6 19.41.2 .9 24.9 32.7 Cumulative Results 15 1.9 18.0 13.7.8 .8 27.9 38.6 EXAMPLE 1~
Indium nitrate (1.7 grams) was dissolved in 100 ml. water. This solution was then added to 9.5 grams of Houdry HSC 534 silica and allowed to stand Eor 1 hour. The mixture was slowly taken to dryness with gentle warming followed by heating at 110C. in a drying oven for 2 hours.
The solid was then heated to 700C at 2/minute and held at 700C. for 10 hours in air to give a finished indium oxide/
silica solid containing 5 weight % indium. The finished solid (207 grams) was charged to a quartz tube of 0.5 inch inside diameter surrounded by a tubular furnace. The contact zone temperature was raised to 700C. under flowing nitrogen. Nitrogen flow was stopped and methane was intro-- duced into the reactor at a rate of 100 ml/min. (i.e., a gas hourly space velocity of 860 hrsO~l GHSV~. Reactor effluent was sampled at the reactor exit and analyzed on a gas chromatograph at a number of time intervals. In addi-tion, all reactor effluent was collected in a sample bag for subsequent analysis of the cumulative reaction products Results (obtained at about atmospheric pressure) are shown in Table XVI below, 7~8 TABLE XVI
% Selectivity Time (min.) Conversion C2~4 ~ C~ ~2 Instantaneous Results 1 0.73 10.9 21.9 0.366.9
` :
acetylene-containing gas and thereby making acetylene recovery difficult.
The largest, non-fuel use of methane is in the production of ammonia and methanol ~and formaldehyde)~ The first; methane conversion, step of these processes is the production of a synthesis gas ~CO + H2) by reforming of methane in the presence of steam overr for example, a nlckel catalyst. Typlcal reformers are tubular furnances ; heated with natural gas, the temperature being maintained at 900C and the pressure at about 225 atmospheresO
Pyrolytic or dehydrogenataive conversion of methane or natural gas to C2+ hydrocarbons has previously ` been proposed. The conversion required high temperatures `~ (greater than about 1000C.) and is characterized by the ,~ formation of by~product hydrogen. ~he patent literature contains a number of proposals to catalyze pyrolytic l reactions, allowing conversion at lower temperatures. See, 1~ for example, U.S. Patent Nos. 1,656l813; 1,687,890;
~` 1,851,726 1,863,212; 1,922,960; 1~958,648; 1,986,238 and 1,988,873. U.S. Patent 2,436,595 discloses and claims a : `
catalytic, dehydrogenative methane-conversion process which employs fluidized beds of heterogeneous catalysts comprising an oxide or other compound of the metals of group VI or VIII.
Including oxygen in a methane feed for conversion over metal oxide catalysts has been proposed. Margolis, L.
Ya., Adv. Catal. 14/ 429 (1963) and Andtushkevich, T.V., et al, Kinet. Katal 6, 860 (1965) studied oxygen-methane cofeed over different metal oxides. ~hey report the forma-tion of methanol, formaldehyde, carbon monoxide and carbon ~2~
dioxide from methane/oxygen feeds. Higher hydrocarbons are either not formed or are converted much faster then methane.
Fatiadi has prepared an extensive review of reactions in which manganese dioxide is used for mild, selective heterogeneous oxidation of numerous classes of organic compounds. The us~ of manganese dioxide to form higher hydrocarbon products from methane is not mentioned.
Fatiadi, A. J., "Active Manganese Dioxide In organic Chemistry - Part I", Synthesis, 1976, ~o. 2, pp. 65, et seq.
(February, 1975); Fatiadi, A. J., "Active Manganese Dioxide In Organic Chemistry - Part II", Synthesis, 1976, No. 3, pp. 113, et seq. (March, 1976).
It has been reported that manganese oxide forms manganese carbides from methane at 800~. Fisher, F., et al, Brenstoff - Chem., 10, 261 (1929).
SUMM~RY OF THE INVENTION
It has been found that methane may be converted to higher hydrocarbon products by contactiny a methane-containing gas with oxides of manganese, tin, indium, germanium, lead, antimony and/or bismuth at temperatures selected within the range of about 500 to 1000C. Hydro-carbons produced include lower alkanes, lower olefins and aromatics. The oxides are reduced by the methane contact and are easily reoxidizable by contact with an oxygen-containing gas.
The present process is distinguished from previously known pyrolytic methane conversion processes by the use of the aforementioned reducible oxides to synthe-size higher hydrocarbons from methane with coproduction of water, rather than methane.
The present process is distinguished from previously suggested methane conversion processes which rely primarily on interactions between methane and at least one of nickel and the noble metals, such as rhodium, palladium, silver, osimum, iridium, platinum and gold. An example of this type of process is disclosed in U.S. Patent ~,205,194. The present process does not require that methane be contacted with one or more of nickel and such noble metals and compounds thereof.
Moreover, in a preferred embodiment, such contac-ting is carried out in the substantial absence of catalyt-ically effective nickel and the noble metals and compounds thereof to minimize the deleterious catalytic effects of such metals and compounds thereof. For example, at the conditions, e.g., temperatures, useful for the contacting step of the present invention, these metals when contacted with methane tend to promote coke formation, and the metal oxides when contacted with methane tend to promote forma-tion of combustion products (COx) rather than the desired hydrocarbons. The term "catalytically effective" is used herein to identify that qua~tity of one or more of nickel and the noble metals and compounds thereof which when present substantially changes the distribution of products obtained in the contacting step of this invention relative to such contacting in the absence of such metals and compounds thereof.
Oxides of manganese which are reduced when contacted with methane at a temperature of about 500-1000C.
include MnO2, Mn2O3, Mn3O4 or mixtures thereof. However, it has been further discovered that, of these reducible oxides of manganese, Mn3O4 is the most effective in promot-ing high yields of hydrocarbon products. The spinel, Mn3O4, is known to be formed by oxidation/decomposition of manganese compounds at temperatures above about 900C. and can be stabilized at lower temperatures, e.g., by being supported on silica.
A preferred oxide of tin is SnO2.
A preferred oxide of indium is In2O3.
A preferred oxide of germanium is GeO2.
A preferred o~ide Gf lead is PbO.
A preferred oxide of antimony is Sb2O3.
A preferred oxide of bismuth is Bi2O3.
It has been further found that use of elevated pressures (i.e., pressures greater than atmospheric) in the methane contact zone of processes employing one or more of the aforementioned reducible oxides promotes the formation of C3+ hydrocabon products (i.e., hydrocarbons having three or more carbon atoms per molecule). According to this distinct embodiment of the present invention, methane contact zone pressures are preferably within the range of about 2 to 100 atmospheres, more preferably within the range of about 3 to 30 atmospheres.
The conversion of methane to higher hydrocarbons by contact with oxidative synthesizing agents involves multiple reactions which are not clearly understood.
However, gas-(or vapor-) phase reaction products may be generally characterized as: (1) hydrocarbon products and (2) combustion products. Hydrocarbon products include al~anes, olefins and aromatics. The process is distin-guished from pyrolytic methane conversion processes by the coproduction of water, rather than hydrogen, and by the competing combustion reactions occurring during methane contacting.
A further distinct embodiment of the presently claimed invention resides in the discovery that improved results (e.g., production of hydrocarbon products while reducing the formation of combustion products during methane-contacting) are obtained by employing a process wherein solids (i.e., solid particles) are recirculated between two physically separate zones: a methane contact zone and an oxygen contact zone~ Desirable product distri-butions may advantageously be obtained if particles compri-sing an oxidative synthesizing agent and a gas comprising methane are continuously introduced (e.g., at independently chosen feed rates) into the methane contact zone, which zone is maintained at selected contact temperatures.
Moreover, maintaining fluidized beds o solids in the two contact zones enables control of average solids residence time in each zone and promotes mixing of the two-phase mixtures present in the zones. Average residence time of the methane-containing feed is also controlled. This mode of operation further improves product composition and reduces the formation of combustion products in the methane contact zone, especially when compared to cyclic processes involving intermittent or pulsed flow of methane and oxygen over solids maintained in a single contact zone or when ~2~4~
compared to processes wherein oxygen and methane are cofed over metal oxide catalysts.
Moreover, the process of the present invention provides the capability of producing a substantially uniEorm stream of desirable hydrocarbon products from relatively easily combustible material--methane--while employing oxidative synthesizing agents which are reduced during the methane-contacting. Such substantially uniform hydrocarbon product streams result in, for example, more effective and easier separation of products.
This invention is further described in the following detailed description of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a plot of methane conversion and hydrocarbon product selectivity vs. time for the results reported in Example 3.
Figure 2 is a plot o methane conversion vs. time for the results reported in Examples 2 and 5.
Figure 3 is a plot of ~ C converted and hydro-carbon product selectivity vs. run time for the results reported in Example 10.
Figure 4 is a plot of ~ C converted and hydro-carbon product selectivity vs. run time Eor the results reported in Example 11.
Figure 5 is a plot of methane conversion and hydrocarbon product selectivity vs. time for the results reported in Example 13.
Figure is 6 a plot of methane conversion vs. time for the results reported in Example 13 and 14.
Figure 7 is a plot of methane conversion and 12~9~7~38 hydrocarbon product selectivity vs. time for the results reported in Examples 16 and 17.
Figure 8 is a plot of methane conversion and hydrocarbon product selectivity vs. time for the results reported in Example 18.
Figure is 9 a plot of methane conversion and hydrocarbon product selectivity vs. time for the results reported in Examples 19.
Figure 10 is a plot of methane conversion to gaseous products and C2+ hydrocarbon product selectivity vs. time for the combined results of Examples 20 and 21.
Figure is 11 a plot of methane conversion to gaseous products and ~2+ hydrocarbon product selectivity vs. run time for the results of Example 22.
Figure 12 is a plot of methane conversion and hydrocarbon selectivity vs. time for the results of Examples 23 and 24.
Figure 13 is a plot of methane conversion and hydrocarbon product selectivity vs. time for the results of Example 25.
Fi~ure 14 is a plot of methane conversion and hydrocarbon product selectivity vs. time ~or the results reported in Example 26.
Figure 15 is a plot of methane conversion and hydrocarbon product selectivity vs. run time for the results of Example 27.
~ igure 16 is a plot of methane conversion vs.
time for the results reported in Examples 22 and 28.
Fi~ure 17 is a plot of methane conversion and hydrocarbon product selectivity vs. time for the results of Example 30.
_ ~ _ ~2a~
Figure 18 is a plot of methane conversion vs.
time for the results of Examples 30 and 31.
Figure 19 is a plot of the ratio, ~ yield of C
hydrocarbon products/% yield of C2+ hydrocarbon products, vs. run time for the instantaneous results obtained in Examples 33 and 34 and Comparative Example A.
DETAILED DESCRIPTION OF THE INVENTION
_ Oxidative synthesizing agents are compositions comprising at least one oxide of at least one metal, which composition r when contacted with methane at a temperature selected within the range of about 500 to 1000C, produces C2+ hydrocarbon products, coproduct water, and a composi-tion comprising a reduced metal oxide. The composition of the oxidative synthesizing agent thus contains at least one reducible oxide of at least one metal. The term "reducible"
is used to identify those oxides of metals which are r~duced by contact with methane at tempera~ures selected within the range of about 500 to 1000C. The term "oxide(s) of metal(s)" includes: (1) one or more metal oxides (i.e., compounds described by the general formula MxOy wherein M
is a metal and the subscripts x and y designate the relative atomic proportions of metal and oxygen in the compound) and/or (2) one or more oxygen containing metal compounds, provided that such oxides and compounds have the capability of performing to produce higher hydrocarbon products as set -forth herein. Preferred oxidative synthe-sizing agents comprise reducible oxides of metals selected from the group consisting of Mn, Sn, In, Ge, Pb, Sb, and Bi, and mixtures thereof. Particularly preferred oxidative synthesizing agents comprise a reducible oxide of manganese and mixtures of a reducible oxide of manganese with other oxidative synthesizing agents. More preferred are oxida-tive synthesizing agents which comprise Mn3O~. Among the reducible oxides of manganese, those containing major amounts of Mn2O3 and Mn3O4 are preferred~ As noted, a particularly preferred class of oxidative synthesizing agents are those comprising Mn3O4. Among the reducible oxides of tin, those containing major amounts of SnO2 are preferred. Among the reducible oxides of indium, those containing major amounts of In2O3 are preferred. Among the reducible oxides of germanium, those containing major amounts of GeO2 are preferred. Among the reducible oxides of lead, those containing major amounts of PbO are pre-ferred. Among the reducible oxides of antimony, those containing major amounts of Sb203 are preferred. Among the reducible oxides of bismuth, those containing major amounts of Bi2o3 are preerred.
Reducible oxides are preferably provided as particles. They may be supported by, or diluted with, a conventional support material such as silica, alumina, titania, zirconia, and the like, and combinations thereof.
A presently preferred support is silica.
Solids may be formed in conventional manner using techniques well known to persons skilled in the art. For example, supported solids may be prepared by conventional methods such as adsorption, impregnation, precipitation, coprecipitation, or dry-mixing.
A suitable method is to impregnate the support with solutions of a compound containing the metal. Some examples of metal compounds are the acetate, acetyl-~L2~
acetonate, oxide, carbide, carbonate, hydroxide, formate, oxalate, nitrate, phosphate, sulfate, sulfide, tartrate, fluoride, chloride, bromide or iodide. Such compounds may be dissolved in water or other solvent and the solutions combined with the support and then evaporated to dryness.
Preferably, aqueous solutions are employed and water-soluble compounds are usedO In some cases, the solutions may have acids and/or bases added to them to facilitate dissolution of the precursors of the metal oxide. For example, acids such as hydrochloric or nitric acid or bases such as ammonium hydroxide may be used as desired. The dried solids may then be screened or otherwise processed to form the desired shape, size, or other physical form of the finished solids. Finally, the solids are prepared for use by calcination at high temperatures for a period of time in accordance with conventional practice in this art. For example, the solids are placed in an oven or kiln, or in a tube through which oxygen (e.g., air or oxygen diluted with other gases) is passed, at an elevated temperature selected within the range of about 300 to 1200C. Particular calcin-ation temperature will vary depending upon the particular metal compound.
For solids comprising reducibl~ oxides of manganese, the calcination temperature should be within the range of about 500 to 1200C, preferably about 700 to 1200C, more preferably about 900 to 1200C. Use of higher calcination temperature promotes the formation of Mn3O4 in the finished solid.
For solids comprising reducible oxides tin, the calcination temperature should be within the range of about _ 12 -300 to 1200C, preferably about 500 to 1100C.
For solids comprising reducible oxides of indium, the calcination temperature should be within the range of about 300 to 900C, preferably about 500 to 850C.
For solids comprising reducible oxides of germanium, the calcination temperature should be within the range of about 300 to 1200C, preferably about 500 to 1000C.
For solids comprising reducible oxides of lead, the calcination temperature should be within the range of about 300 to 1000C, preferably about 500 to g00C. Use of higher calcination temperatures promotes the formation of PbO in the finished solid.
For solids comprising reducible oxides of antimony, the calcination temperature should be ~7ithin the range of about 300 ~o 1200~C, preferably about 500 to 850.
For solids comprising reducible oxides of bismuth, the calcination temperature should be within the range of about 300 to 1000~C, preferaby about 500 to 850C.
The foregoing description regarding preparation of reducible oxides of manganese, tin, indium, germanium, lead, antimony and bismuth in a form suitable for the synthesis of hydrocarbons from a methane source is merely illustrative of many possible preparative methods, although it is a particularly suitable method and is preferred.
Metal loadings on supported solids may be within the range of about 1 to 50 wt. % (calculated as the elemental metal(s) o the reducible oxides(s~.
In addition to methane, the feedstock employed in the method of this invention may contain other hydrocarbon ~ 13 -of nonhydrocarbon components, although the methane content should be within the range of about 40 to 100 vol. %, preferably from about ~0 to 100 vol. ~, more preferably from about 90 to 100 vol. ~.
Operating temperatures for the contacting of methane-containing gas and the oxidative synthesizing agent are selected from the range of about 500 to 1000C, the particular temperature selected depending upon the partic-ular oxide(s) employed in the oxidative synthesizing agent.
For example, all oxidative synthesizing agents have the capability of synthesizing higher hydrocarbons from a methane source when the temperature of the methane-contact are selected within the lower part of the recited range. Reducible oxides of certain metals, however, may require operating temperatures below the upper part of the recited range to minimize sublimation or volatilization of the metals (or compounds thereof) during methane contact.
Examples are: (1) reducible oxides of indium (operating temperatures ~7ill pr~ferably not exceed about 850C); (2) reducible oxides of germanium (operating temperatures will preferably not exceed about 800C); and (3) reducible oxides of bismuth (operating temperatures will preferably not exceed about 850C).
Operating temperatures for the contacting of methane-containing gas and a reducible oxide of manganese are in the range of about 500 to 1000C., preferably within the range of about 600 to 900C.
Operating temperatures for the contacting oE
methane-containing gas and a reducible oxide of tin are in the range of about 500 to 1000C., preferably within the range of about 600 to 900C.
Operating temperatures for the contacting of methane-containing gas and a reducible oxide of indium are in the range of about 500 to 850C., preferably within the range of about 600 to 800C.
Operating temperatures for the contacting of methane-containing gas and a reducible oxide of germanium are in the range of about 500 to 800C., preferably within the range of about 600 to 750C.
Operating temperatures for the contacting of methane-containing gas and a reducible oxide of lead are in the range of about 500 to 1000C., preferably within the range of about 600 to ~00C.
Operating temperatures for the contacting of methane-containing gas and a reducible oxide of antimony are in the range of about 500 to 1000C., preferably within the range of about 600 to 900C.
operating temperatures for the contacting of methane-containing gas and a reducible oxide of bismuth are in the range of about 500 to 850C., preferably within the range of about 600 to 800C.
Operating pressures for the methane contacting step are not critical to the broadly claimed invention.
However, both general system pressure and the partial pressure of methane have been found to effect overall results.
A distinct embodiment of the present invention is a method wherein an oxidative synthesizing agent comprising a reducible metal oxide is contacted with me-thane, the further improvement residing in the use of elevated pressures to promote the formation of C3+ hydrocarbon products. Operating pressures for the methane contacting step of this invention are preferably within the range of about 2-100 atmospheres, more preferably about 3-30 atmos-pheres. Elevated pressures have been found to provide improved results, e.g., elevated pressures promote forma-tion of C3+ hydrocarbon products.
Contacting methane and an oxidative synthesizing agent to form higher hydrocarbons from methane also reduces the oxidative synthesizing agent and produces coproduct water~ The exact nature of the reduced forms of oxidative synthesizing agents are unknown, and so are referred to herein as "reduced synthesizing agent" or as "a reduced metal oxide". Regeneration of a reducible oxide is readily accomplished by contacting reduced compositions with oxygen (e.g., an oxygen-containing gas such as air) a~ a tempera-ture selected within the range of about 300 to 1200C., the particular temperature selected depending on the particular metal(s) included in the oxidative synthesizing agent. The contact time should be sufficient to produce a reducible oxide from at least a portion of the reduced composition.
Oxygen contacting temperatures for reduced oxides of manganese are preferably within the range of about 300 to 1200C., more preferably within the range of about 700 to 1200C.~ still more preferably within the range of about 900 to 1200C. Higher reoxidation temperatures promote formation of Mn3O4, the preferred reducible oxide of manganese.
Oxygen contacting temperatures for reduced oxides of tin are preferably within the range of about 300 to ~L2~
1200C., more preferably within the range of about 500 to 1100C.
Oxygen contacting temperatures for reduced oxides of indium are preferably within the range of about 300 to 900C., more preferably within the range of about 500 to 850C. Higher reoxidation temperatures promote formation of In2O3, the preferred reducible oxide of indium.
Oxygen con~acting temperatures for reduced oxides of germanium are preferably within the range oE about 300 to 1200C., more preferably within the range of about 500 to 1000C.
Oxygen contacting temperatures for reduced oxides of lead are preferably within the range of about 300 to 1000C., more preferably within the range of about 500 to 900C. Higher reoxidation temperatures promote formation of PbO, the preferred reducible oxide of lead.
Oxygen contacting temperatures for reduced oxides of antimony are preferably within the range of about 300 to 1200C., more preferably within the range of about 500 to 850C~
Oxygen contacting temperatures for reduced oxides of bismuth are preferably within the range of about 300 to 1200C., more preferably within the range of about 500 to 850C.
Particles comprising a reducible oxide of Mn, Sn, In, Ge, Pb, Sb or Bi may be contacted with methane in fixed, moving, fluidized, ebullating, or entrained beds of solids.
Preferably, methane is contacted with a fluidized bed of particles comprising the said reducible oxides.
Similarly, particles comprising a reduced oxide of Mn, Sn, In, Ge, Pb, Sb~ or ~i may be contacted with oxygen in fixed, moving, fluidized, ebullating or entrained beds of solids. Preferably, oxygen is contacted with a fluidized bed of particles comprising the reduced oxides.
A single reactor apparatus containing a fixed bed of solids, for examplel may be used with intermittent or pulsed flow of a first gas comprising methane and a second gas comprising oxygen ~e.g., oxygen, oxygen diluted with an inert gas, or air, preferably air).
Preferably, however, the methane contacting step and the oxygen contacting step are performed in physically separate zones with particles recircula~ing between the two zones. Thus, the preferred method for synthesizing hydro-carbons from a methane source comprises: (a) contacting in a first zone a gas comprising methane and particles compri-sing an oxidative synthesizing agent to form higher hydro-carbon products, coproduct water, and reduced synthesizing agent; (b) removing particles comprising reduced synthe-sizing agent from the first zone and contacting the reduced particles in a second zone with an oxygen-containing gas to form particles comprising an oxidative synthesizing agent; and (c) returning the particles produced in the second zone to the first zone.
Particles comprising an oxidative synthesizing agent which are contacted with methane may be maintained as fluidized, ebullating, or entrained beds of solids. Prefer-ably, methane is contacted with a 1uidized bed of solids.
Similarly, partic~es comprising reduced synthes-izing agent which are contacted with oxygen may be main-tained as fluidized, ebullating or entrained beds of solids.
Preferably, oxygen is contacted with a fluidized bed of solids.
Thus, in a presently preferred embodiment of the present invention, methane feedstock and particles compri-sing an o~idative synthesiæing agent are continuously introduced into a methane contact zone maintained at synthesizing conditionsO Synthesizing conditions include the temperatures and pressures described above. The methane feedstock is introduced at sufficient velocity such that the particles are fluidized~ Gaseous reaction products from the methane contact zone (separated from any ~ntrained solids) are further processed--e.g., they are passed through a fractionating system wherein the desired hydrocarbon products are separated from unconverted methane and combustion products. Unconverted methane is preferably recovered and recycled to the methane contact zone.
Of considerable importance to the process of this invention is the average residence time of particles in the methane contact zone. Selection of a desired solids resi-dence time is dependent on the particular reducible metaloxide(s) incorporated in the particles comprising an oxida-tive synthesizing agent, the concentration of such active component, the feedrate and composition of the methane feedstock, and other operating conditions (esp. temperature and pressure of the contact zone). Preferably, the average residence time of particles in the fluidized bed contact zone is within the range of about 0.04 to 30 minutes, more preferably about 0.4 to 4 minutes. Optimum solids resi-dence times for any particular oxidative synthesizing agent will decrease as methane contact temperatures, gas eed ~20~
rates or hydrocarbon concentrations in the feed increase.
The feed rate of methane feedstock is related to the average residence time of particles, comprising an oxidative synthesizing agent, in the methane contact zone.
Preferably, residence time of methane feedstock in the methane contact zone is within the range of abou-t 0.1 to 100 seconds, more preferably about 1 to 20 seconds.
The SiZ2 of particles comprising an oxidative synthesizing agent is preferably selected to render those particles capable of fluidization, preferably in a dense phase, in the methane contact zone. These particle sizes are usual and are not peculiar to this invention.
Particles comprising reduced synthesizing agent are contacted with molecular oxygen in an oxygen contact zone for a time sufficient to restore or maintain the activity of the agent by oxidizing at least a portion of the reduced metal oxide to produce a reducible oxide and by removing, i.e., combusting, at least a portion of any carbonaceous deposit which may form on the particles in the methane contact zone. The conditions of the oxygen contact zone will preferably include a temperature selected within the range of about 300 to 1200C, pressures up to about 30 atmospheres, and average particle contact times within the range of about 3 to 120 minutes. Sufficient oxygen is preferably provided to oxidize all reduced metal oxide to produce a reducible oxide and to completely combust any carbonaceous deposit material deposited on the particles.
At least a portion of the particles comprising an oxidative synthesizing agent, which are produced in the oxygen 0 contact zone are returned to the methane contact zone.
- 20 ~
The rate of solids withdrawal from the methane contact zone is desirably balanced with the rate of solids passing from the oxygen contact zone to the methane contact zone so as to maintain a substantiall~ constant inventory of particles in the methane contact zone, thereby enabling steady state operation of the synthesis systemO
The invention is further illustrated by reference to the following examples.
Experimental results reported below include conversions and selectivities calculated on a molar basisO
Solids productivity, reported as g/g-hr., is grams of methane converted to C2~ hydrocarbon products/gram of solid oxidative synthesizing agent/hour.
The supported manganese oxides employed in Examples 1-11 were made by impregnating the appropriate amount of manganese, as manganeous acetate, onto the supports from water solutions. Supports used were Houdry ~SC 534 silica, Cab-O-Sil, Norton alpha-alumina and Davison gamma-alumina. The impregnated solids were dried at 110C for 4 hours and then calcined in air at 700C for 16 hours. Composition of the calcined solids is identified as "wt. % Mn/(support)".
Methane-contact runs described in Examples 1-11 were made at about atmospheric pressure in a quartz tube reactor (12 mm. inside diameter) packed with 10 ml~ of catalyst. The reactors were brought up to temperature under a flow of nitrogen which was switched to methane at the start of the run. Instantaneous samples of the effluent were taken throughout the run and analyzed by gas chromatography and gas chromatography- mass spectroscopy.
8~3 A cumulative run sample was also collected.
Examples 1-4 demonstrate the effect of manganese oxide loading on methane conversion. Total conversion is shown to bear a distinct relationship to loading.
A feed of 100% methane was passed over a bed of 5 wt. % Mn/SiO2 according to the procedure described above.
Contact zone temperature was 800C and the GHSV (gas hourly space velocity) was 600 hrs~l. Results are reported in Table I below. No carbon formation was detected on the solid present at the end of the run.
TABLE I
Time % _ % Selectivity (min) conv. CH2CH2 CH~CH~ C
Instantaneous Results 1 4.00 2~.5 37i4 1.991.8 19.9 21.0 2 1.02 17.6 59.8 1.47trace 14.3 4 .243 20.5 77.3 2.05 8 .166 22.2 74~6 3.0 .134 26.8 67.9 5.2 Cumulative Results 30 .429 27.2 45.~ 2.9 g.7 9.1 A feed of 100% methane was passed over a bed of 10 wt. % Mn/SiO2 according to the procedure described above.
Contact zone temperature was 800C and the GHSV was 600 hrs~l. Results are reported in Table II below. No carbon formation was detected on the solid present at the end of the run.
~2~7~
TABLE II
Run Time % % Selectivity (min) Conv. CH~CH2 CH3CH3 C~ C _ O~
Instantaneous Results * 1 Z2.4 40.7 18.2 2~1 17.1 18.9 4 .85 28.g 48.6 22.4 12 .32 3~.6 36.6 26.7 30 .27 56.7 43.2 Cumulative Results 1030 1.77 24.5 23~9 24O4 26.4 * Solids Productivity (Instantaneous) = 0.145 g/g hr.
A feed of 100~ methane was passed over a bed of 15 wt. % Mn/SiO2 according to the procedure described above.
Contact zone temperature was 800C and the GHSV was 600 hrs~l. Results are reported in Table III below. No carbon formation was detected on the solid present at -the end of the run. Figure 1 is a plot of % methane conversion and selectivity to C2+ hydrocarbon products vs. run time.
TABLE III
Run Time % % Selectivity (min) Conv. CH2CH2 CH~CH~ C~ C4-C7 CO CO~
Instantaneous Results -* 1 30.1 36.5 13.9 2.15 3.56 19.5 24.2 2 12.3 42.9 27.0 17.0 12.9 12 .402 55.8 44.1 30 .308 51.8 41.8 Cumulative Results 30 2.27 31.8 23.9 15.8 28.3 * Solids Productivity at 1 min = 0.157 g/g hr.
~7~
A feed of 100% methane was passed over a bed of 50 wt. % Mn/SiO2 according to the procedure described above.
Contact zone temperature was 700C and the GHSV was 600 hrs~l. Results are reported in Table IV below. No carbon formation was detected on the solids present at the end of the run.
TABLE IV
P~un Time % % Selectivity (min) Conv. CH~CH~ CH~CH~ c3 CO CO2 Instant~neous Results _ 1 22 D 8 2.3 3.46 .01 94.2 2 11.6 3.5 9.37 .05 .17 86.8 4 7.39 4.44 1~.8 .08 81O1 12 2.31 5.76 22.0 ~13 .~6 71.1 1.08 11.9 22.0 .36 65.6 Cumulative Results -30 4~12 4.26 12~5 .09 .36 82.6 This example demonstrates the recyclability of the Mn oxide, oxidative synthesizing agent of this inven-tion. The reduced solid remaining at the end of the run described in Example 2 was regenerated under a flow of air at B00C. for 30 minutes. The reactor was then flushed with nitrogen. The regenerated, reoxidized solids were then contacted with methane at a temperature of 800C and a GHSV of 600 hrs.~l. Results are shown in Table V below.
No carbon oxides were ~etected during the oxidation of the reduced solids. Comparison of the results reported in Tables II and V indicates substantially complete recovery of Mn oxide activity for the conversion of methane to higher hydrocarbons. Figure 2 is a plot of methane conver-sion vs. time for the combined results of Examples 2 and 5.
TABLE V
Run Time % % Selectivity (min) Conv. CH2(::H2 CH3CH3 ~ C0 Instantaneous Results 21.1 38.9 1705 2.4 18.8 lg.9 4 1.05 26.1 ds2~3 31.5 1012 .42 40.9 26.9 29.8 30 .36 64.8 35.2 Cumulative Results 30 1.56 25~2 18.1 1.3 24.7 30.7 The runs of this example show the effect of temperature on the conversion process of this invention. A
feed of 100% methane was passed over a bed of 5 wt. %
Mn/SiO2 at a GHSV of 600 hr. 1. Results obtained at various contact temperatures are shown in Table VI below.
TABLE VI
Run A
Time % % Selectivity TempC (min) conv. CH2CH2 CH3CH3, ~ C4-C6 C0 Instantaneous Results 650 2 1.25 2.4 19.1 trace 39.0 39.4 4 .28 503 62.1 27.5 16 .081 8~6 91.3 30 .03 15.8 84.1 Cumulative Results 3030 .223 6.7 52.0 21.5 19.7 Run ~
Time % % Selectivity TempC tmin) conv.CH2CH2 CH3CH3C3 C4-C~ CO C~2 Instantaneous Results 700 2 1.95 10.5 39.2 .9 23.0 26.1 4 .896 9.9 53.5 .08 27.5 8 .31 1370 87.1trace 16 .08713.7 86.2 .03 16.6 83.3 Cumulative Results 30 .319 14.1 67.1 9.4 9.
Run C
Temp~C (min) conv. CH2CH2 ~L3~ 5~ CO ~2_ Instantaneous Results 750 2 2.65 18.2 ~4.0 1.5 19.9 16.3 4 .5g6 15.1 81.0 1.3 2.5 8 .164 1~.6 85.3 16 .053 16O9 83.0 .041 17.0 ~3.0 Cumulative Results 30 .379 23.7 57.8 2.1 9.23 7.12 Example 1, supra, shows results of a similar run at 800C.
Initial and cumulative conversions increase with tempera-ture over the range of temperatures studied. Selectivities to higher, C3+, hydrocarbons tend to increase with tempera-ture as does the ratio of olefinic (e.g., ethylene) to paraffinic (e.g., ethane) hydrocarbon products. Formation of C3~ hydrocarbon products is promoted by higher tempera-tures.
~7~
Example 1 was repeated except that during prepar-ation of the supported Mn oxide, the dried impregnated catalyst was calcined in air at 1000C and the methane feed contained 16 vol. % methane, the remainder being N2.
Contact temperature was 750C and GHSV was 600 hrs.-l.
Results are shown in Table VII below. X-ray diffraction analysis of the calcined solid indicated that Mn was present as Mn3O4.
TABLE VII
Run Time % % Selectivity (min) Conv. CH2CH2 CH3CH3 ~_ CO C02 Instantaneous Results 1 12.7 - 15.7 17.5 .39 19.0 47.3 2 10.1 18.7 27.9 .49 21.6 31.1 4 2.59 19.7 47.7 ~77 16.5 15.26 12 1.02 12.3 49.1 .48 38.1 .289 32.8 65.4 1.73 Cumulative Results 30 2.96 17.4 13.7 .23 24.3 44.28 Example 3 This example demonstrates the effect of space velocity on the methane conversion process of this inven-tion. The procedure of Example 2 was repeated in the two Runs described in Table VIII below except that the space velocity of Run A was 1200 hrs -1 and space velocity of Run B was 300 hrs -1.
TABLE VIII
Run A
Run Time % % Selectivity (min) Conv. C2H4 ~2~h C3 C4-C7 CO CO~
Instantaneous Results -~5 5~25 22~2 ~0~3 ~15 27~0 8~8 1~0 o81 18~4 78~7 ~85 1~9 4~0 ~10 15~8 84~1 15.0 ~ 08 22 ~ 6 77 ~ 3 Cumulative Results -15 ~335 25~9 52~2 2~7 8~35 10~7 Run B
Run Time % % Selectivity (min) Conv. ~2~ C2H6 ~ C4-C7 CO ~2_ Instantaneous Results 1 37~ 20~1 4~6 1~20~7 48~1 25~3 2 l9.B 24.1 18.6 2.80~4 45~2 10~7 4 3~54 35~8 34~0 1~5~5 28~2 12 2~21 34~7 55~0 1~5 0 8 1.75 30 ~ 0 68 ~ 7 1.3 Cumulative Results _ 30 3~85 33~2 19~2 1~4 ~2 35~8 10~2 Example 9 Each of the following runs were made over 10 ml.
catalyst with a 14-16 vol. ~ CH4 in N2 feed. The feed rate (calculated at standard conditions) was 100 ml/min, equiva-lent to a GSHV Of 600 hrs~l. In Run A, the solid contact-ing agent was 5 wt. %Mn/gamma alumina and the contacting zone tempe-rature was 750C~ In Run B, the solid contacting 30 agent was 5 wt. % Mn/alpha-alumina and the contacting zone ~ 28 ~
7~
temperature was 750C. In Run C, the solid contacting agent was 5 wt. % Mn/SiO2 solids which had been subjected to at least 10 methane contact/oxidation cycles. In the oxidation portion of these cycles, reduced solids from the methane-contacting portion of the cycle were regenerated under a flow of air at 700C for 15 to 30 minutes and the reactor was then flushed with nitrogen before starting the next methane run. The contacting zone temperature for Run C was 700C. The results reported in Table IX are cumula-tive results obtained over a 30 minute contact time. X-ray diffraction analysis of the solid contacting agent used in Run C indicated that Mn was present as Mn3O
TABLE IX
Solids Productivity % ~ Selectivity x 103 Run# Conv. ~ C CO~2 (g/g-hr) A 6.12 11.4 .48 31.754.5 1.06 B 9.64 6.56 12.9 .07 80.3 0.95 C 1.23 12.0 51.6 .85 19.615.8 1.49 Example 10 A feed of 95 vol. % methane and 5 vol. % ethane was passed over a bed of 5 wt. ~ Mn/SiO2 according to the procedure described above. The contact temperature was 700C and the G~SV was 860 hrs~l. Unlike the runs described in the previous examples, a carbonaceous, coke-like deposit was present on the solids at the end of an 11 minute run. The results for the run, reported in Table X, below, are based on C in the feed converted to gas phase products only and do not take coke formation into account.
The amount of carbonaceous deposit formed over the 11 7~
minute run was 14.8% of all feed converted. Figure 3 is a plot of % C converted and % selectivity to C2+ hydrocarbon products vs. run time for the results of this example.
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7~8 Example 11 A feed of 95 vol. % methane and 5 vol. % ethylene was passed over a bed of 5 wt. % Mn/SiO2 according to the procedure described above. The contact temperature was 700C and the GHSV was 860 hrs~-l. A carbonaceous, coke-like deposit was present on the solids at the end of an 11 minute run. The amoun-t of carbonaceous deposit formed was 35.6% of all feed C converted. A wax-like condensate was also noted at the reactor outlet. The amount of this condensate was 5.0% of all feed C converted, Results for the run are tabulated in Table XI, Figure 4 is a plot of %
C converted and % selectivity to C2 + hydrocarbon products vs. run time for this example.
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The supported oxides of tin employed in Examples 12-15 were made by impregnation of tin ~artrate, in an aqueous solution of 7% hydrochloric acid, on Houdry HSC 534 silica, the amount of tin provided being sufficient to yield a solid containing 5 wt. % Sn/SiO2. The solids were dried at 110C for 4 hours and then calcined in air at 700C for 16 hours. The solids employed in the runs described in the examples are equilibrated solids, i.e., solids prepared as described above which have been contacted at least once with methane at a temperature of about 700C and then reoxidized by being contacted with air at about 700C.
Runs described in Examples 12-15 were made in a quartz tube reactor (12 mm. inside diameter) packed with 10 ml. of solids at about atmospheric pressure. The reactors were brought up to temperature under a flow of nitrogen which was switched to methane at ~he start of the run. Instantaneous samples of the effluent were taken throughout the runs and analyzed by gas chromatography and gas chromatography mass spectroscopy.
A feed of 100% methane was passed over a bed of solids as described ~bove. Contact zone temperature was 700C and the GHSV (gas hourly space velocity) was 600 hrs~l. Results are reported in Table XII below. No carbon was detected on the solid present at the end of the run.
~788 TABLE XI I
Run Time % % Selectivity ~min) conv. C2H4 ~ C~ C4-7 CO ~O~
Instantaneous Results .5 3.18 7.2 13.7.2 .8 15.5 62.3 1.0 1.27 8.8 17.2.5 2.7 24.7 45.7 2.0 .25 34,3 52.73.6 9.2 Cumulative Results -15 .23 29.9 29.93.4 8.6 11.0 16.9 A feed of 100% methane was passed over a bed of solids as described above. Contact zone temperature was 750C and the GHSV was 600 hrs~l. Results are reported in Table XIII below. No carbon was detected on the solid present at the end of the run. Figure 5 is a plot of %
methane conversion and % selectivity to C2 + hydrocarbon products vs. run time.
Run Time % % Selectivity (min~ conv. C~H~ fi C C4-7 CO ~2 20Instantaneous Results -.5 7.23 9.9 14.6 .4 .4 9.2 65.4 1.0 1.25 18.2 35.6 .7 1.0 2.3 42.2 2.0 .43 30.7 67.6 1.3 .2 Cumulative Results .
15 .54 24.7 40~8 .9 2.5 13.0 17.8 E_AMPLE 1 4 The reduced solid remaining at the end of the run described in Example 13 was regenerated under a flow of air at 750C for 30 minutes. The reactor was then flushed with nitrogen. The regenerated, reoxidized solids were then contacted with methane at a temperature of 750C and GHSV
of 600 hrsO~l. Resul-ts are shown in Table XIV below. No carbon oxides were detected during the oxidation of the reduced solids. Figure 6 is a plot of methane conversion vs. run time for the combined results of Examples 13 and 14.
TABLE XIV
Run Time % ~ Selectivity (min? _ conv. ~ C2H6 C3 C4-7 CO ~2 Instantaneous Results 10.5 6.52 11.2 1~.8.3 .2 13.5 59.8 1.0 1.10 22.7 34Ø5 .7 15.7 26.3 2.0 .37 32.7 65~21.2 .2 .8 Cumulative Results 15 .48 26.2 35.31.33.~ 12.0 21.9 The procedure of Example 12 was repeated except that contact zone temperature was 800C. Results are shown in Table XV below. No carbon was detected on the solid present at the end of the run.
TABLE XV
Run Time % ~ Selectivity (min? conv- ~2~ C2H6C~ C4-7 CO C02 Instantaneous P~esults .5 10.1 15.7 13.6.8 .9 11.1 57.7 1.0 3.2 26.7 21.11.71.8 18.2 30.3 2.0 2.2 20~6 19.41.2 .9 24.9 32.7 Cumulative Results 15 1.9 18.0 13.7.8 .8 27.9 38.6 EXAMPLE 1~
Indium nitrate (1.7 grams) was dissolved in 100 ml. water. This solution was then added to 9.5 grams of Houdry HSC 534 silica and allowed to stand Eor 1 hour. The mixture was slowly taken to dryness with gentle warming followed by heating at 110C. in a drying oven for 2 hours.
The solid was then heated to 700C at 2/minute and held at 700C. for 10 hours in air to give a finished indium oxide/
silica solid containing 5 weight % indium. The finished solid (207 grams) was charged to a quartz tube of 0.5 inch inside diameter surrounded by a tubular furnace. The contact zone temperature was raised to 700C. under flowing nitrogen. Nitrogen flow was stopped and methane was intro-- duced into the reactor at a rate of 100 ml/min. (i.e., a gas hourly space velocity of 860 hrsO~l GHSV~. Reactor effluent was sampled at the reactor exit and analyzed on a gas chromatograph at a number of time intervals. In addi-tion, all reactor effluent was collected in a sample bag for subsequent analysis of the cumulative reaction products Results (obtained at about atmospheric pressure) are shown in Table XVI below, 7~8 TABLE XVI
% Selectivity Time (min.) Conversion C2~4 ~ C~ ~2 Instantaneous Results 1 0.73 10.9 21.9 0.366.9
3 0.31 22.4 51.3 0.725.6 6 0.23 26.0 73.6 0.4 0.0 11 0.12 34.0 66.0 0.0 0~0 0.10 39.4 60.6 0.0 0.0 Cumulative Results 30 0.21 28.4 47.7 0.223.7 After completion of the run described in Example 16, ethane Elow was stopped and the contact zone was flushed with nitrogen for 30 minutes, and the solids were oxidized under flowing air at 700C for 90 minutes. The effluent produced during reoxidation was monitored for carbon oxides, and none were found, indicating that no carbonaceous deposit was formed during the methane-contact run described in Example 16. The reoxidized solid was then contacted with methane as described in Example 16. Results are shown in Table XVI below. Figure 7 is a plot of methane conversion and selectivity to C2-~ hydrocarbon products vs. run time for the combined results of Examples 16 and 17.
7~
TABLE XVII
% Selectivity Run Time %
(min ) Conversion C~H~ C2H6 C3 ~2 Instantaneous Results 1 0.85 12.8 26.0 0.460.8 3 0.34 21.6 48.4 ~.629.4 6 0.21 31.3 6~.1 0.6 0.0 11 0.13 32.2 67.5 0.3 0.0 0.12 29.6 70.4 0.~ 0,0 Cumulative Results 30 0.25 29.1 50.4 0.3~0.2 The procedure of Example 16 was repeated except that the gas hourly space velocity was reduced to 86 hours~l. Results are shown in Table XVIII below, and a plot of methane conversion and selectivity to C2~ hydro-carbon products vs. run time is shown in Figure 8.
TABLE XVIII
% Selectivity Run Time 20 (min.) Conversion ~ h ~ 2 1 5.41 7.1 4.2 0.188.6 7 1.98 20.7 13.2 0.565.6 12 1.59 21.5 15.8 0.662.1 23 1.20 27.5 20.9 1.749.9 Cumulative Results -30 2.20 16.3 11.5 0.571.7 The procedure of Example 16 was repeated again except that the feed comprised 6 volume per cent methane in nitrogen. Results for the run are shown in Table XIX below.
~2~7~19 Figure 9 is a plot of methane conversion and selectivity to C2+ hydrocarbon products vs. run time.
TABLE XIX
% Selectivity Run Time %
(min.) Conversion C~H4 C2Hk C~ ~2 Instantaneous Results 1 5.6~ 0.8 0.9 0.0 98.3 5 0.32 15.3 31.3 0.2 53.2 12 0.27 12.5 33.~ 0.4 53.6 1029 0.17 13.1 36.1 0.0 50.8 Cumulative Results 30 0.49 10.4 25.6 0.1 63.9 Germanium dioxide (0.36 gram) was dissolved in 100 ml. water over a period of 12 hours. 1Ihis solution was added to 9.5 grams of Houdry HSC 534 silica and allowed to stand for 1 hour. The mixture was slowly taken to dryness with gentle warming, followed by heating at 110C. in a drying oven for 2 hours. The dried solid was then further heated to 700C. at a rate of 2/minute and held at 700C.
for 10 hours to give a product containing 2.5 weight %
germanium. The entire procedure was then repeated using the solid containing 2.5 weight % germanium instead of fresh silica, to give a final germanium oxide/silica solid containing 5 weight % germanium. The finished solid (2.6 grams) was charged to a quartz tube of 0.5 inch inside diameter surrounded by a tubular furnace. The reactor temperature was raised to 700C. under flowing nitrogen.
Nitrogen flow was stopped and methane was introduced into the reactor at a rate oE 100 ml./min. (860 hrs.~l GHSV).
-- ~10 --7~
The reactor effluent was sampled at the reactor exit and analyzed on a gas chromatograph at a number of time intervals. In addition, all reactor effluent was collected in a sample bag for subsequent analysis of the cumulative reaction products. Results (obtained at about atmospheric pressure and 700C.) are shown in Table XX below. The total amount of carbon oxides formed during reoxidation of the solids (see Example 21, infra) was used to calculate the yield of coke (or other carbonaceous deposit) formed on the solid during the methane run. The instantaneous results shown in Table XX are methane conversion to gaseous products and selectivity to these products (i.e~, % of C converted to gas phase products). The cumulative results shown in Table XX include solid ~ormation.
TABLE XX
% Selectivity*
Run Time Conver- Ben-(min.) sion C~H~ h _~ C~ zene CO Coke*
Instantaneous Results 201 0.39 10.4 26.0 1.0 0O3 0.0 62.3 3 0.18 41.3 49.6 5.8 2.5 0.8 0.0 10 0.15 53.3 33.3 6.7 4.7 2.0 0.0 30 0.13 54.2 27.2 11.4 5.4 1.8 0.0 Cumulative Results 30 0.22 31.9 25.2 6.4 3.2 1.4 6.~ 25.9 *Basis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
After completion of the run described in Example 20, the reactor was flushed with nitroyen for 30 minutes ~2~4~7W
and the solid was reoxidized under flowing air at 700C.
for 90 minutes. The reoxidized solid was then contacted with methane as described in Example 20. Results, shown in Table XXI below, are presented in the same manner as described in Example 20. Figure 10 is a plot of methane conversion to gaseous products ancl C2~ hydrocarbon select-ivity (basis: methane conversion to gaseous products) vs.
run time for the s~ombined results of Examples 20 and 21.
TABLE XII
~6 Selectivity*
Run %
Time Conver- Ben-(min.) sion ~L C~H,~ C3 C4,szene CO Coke*
_ . .
Instantaneous Results -~.30 6.8 20.5 0.7 0.3 0.071.7 3 0.19 37.6 5~.6 5.3 3.0 1.5 0.0 0.17 51.3 3201 9.0 5.1 2.5 0.0 0~14 56.4 2400 12.05.4 2.2 0.0 Cumulative Results 30 0.21 34.1 21.0 6.8 3.4 1.3 8.4 25.0 20 *Basis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
The procedure of Example 20 was repeated except that the methane run temperature was increased to 750C.
Results are shown in Table XXII below. Figure 11 shows the time dependence of methane conversion to all gaseous products and to gaseous hydrocarbons.
~97~38 TABLE XXII
% Selectivity*
Run %
Time Conver- Ben-(min.)sion C2H4 ~ C4,s zene CO Coke*
Instantaneous Results ~ 7 . . _ _ _ 1 1.41 38.6 24.6 3.5 2.5 1.9 2~.9 3 1.14 52.4 11.3 5O0 3.0 5.0 23.3 0.96 67.5 10.4 ~.6 4.2 7.2 ~.1 0.32 66.7 22.5 6.7 2.2 1.9 0.0 Cumulative Results 30 1.06 41.1 9.5 4.4 2.3 3.3 8.7 30.7 *Basis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
Lead (II) acetate ~0.92 gram) was dissolved in 100 ml. of water. This solution was added to 9.5 grams of Houdry HSC 534 silica and allowed to stand for one hour.
The mixture was slowly taken to dryness with gentle warming, followed by heating at 110C in a drying oven for 2 hours.
The solid was then heated to 500C at a rate of 2C/minute and held at 500C for 10 hours to give a finished solid containing 5 wt. % lead.
The finished solid (2.8 grams) was charged to a quartz tube (0.5 inch inside diameter) surrounded by a tubular furnace. The reactor temperature was raised to 700C under flowing nitrogen. Nitrogen flow was stopped and methane was introduced into the reactor at a rate of 100 ml./min. (860 hrs.-l G~SV). The reactor effluent was sampled at the reactor exit and analy~ed on a gas chromato-graph at a number of time intervals. In addition, all ~2~4~8~
reactor effluent was collected in a sample bag for subse~
quent analysis of the cumulative reaction products.
Results (obtained at about atmospheric pressure and 700C.) are shown in Table XXIII below. The total amount of carbon oxides formed during reoxidation of the solids (see Example 24, infra) was used to calculate the yield of coke (or other carbonaceous deposit) formed on the solid during the methane run. The instantaneous results shown in Table XXIII are methane conversion to gaseous products and 10 selectivity to these products (i.e., % of C converted to gas phase products). The cumulative results shown in Table XXIII include solid formation.
TABI.E XXIII
% Selectivity*
Run 96 Time Conver- Ben-(min.)sion ~2~ ~ C3 C~ zene CO ~2 Coke*
= .
Instantaneous Results 3.87 12.45.7 0,5 0.3 0.261.719.1 3 0.26 62.533.6 2.7 1.2 0.00.0 0.0 0.12 61.938.1 0.0 0.0 0.00.~ 0.0 0.08 58.341.7 0.0 0.0 0,00.0 0.0 0.08 57.542.5 0.0 0.0 0.00.0 0.0 Cumulative Results 30 0.33 23.1 14.9 0.3 0.2 0,124.07O5 29.9 *~asis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
9~20~7~3 After completion of the run described in Example 23, the reactor was flushed with nitrogen for 30 minutes and the solid was reoxidized under flowing air at 700C.
for 90 minutes. The reoxidized solid was then contacted with methane in the same manner described in Example 23.
Results, shown in Table XXIV below, are presented as in Example 23. Figure 12 as a plot o:E methane conversion to gaseous products and C2+ hydrocarbon product selectivity (basis: methane conversion to gaseous products) vs. run time for the combined results of Examples 23 and 24.
TABLE XXIV
% Selectivity*
.
Run %
Time Conver- Ben-~min.) sion ~2~ C2H~ C3 C4,s zene CO ~2 Coke*
Instantaneous Results 1 3.50 14.35.2 0.2 0.1 0.162.917.2 3 0.2g 54.143O9 1.0 0.7 0.30.0 0.0 0.16 51.24~.0 0.8 0.0 0.00.0 0.0 0.11 51.448.6 0.0 0.0 0.00.0 0,0 0.10 51.0~9.0 0.0 0.0 0.00.0 0.0 Cumulative Results 30 0.31 25.3 23.1 0.5 0.3 0.119.2 7.4 25.0 *Basis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
Example 23 was repeated except that the GHSV was 86 hrs.~l, Results are shown in Table XXV below and are plotted as a function of run time in Figure 13.
- ~5 -TABLE XXV
% Selectivity*
Run Time Conver-Ben- Tol-(min.) sion ~2~ C2H6 C3 ~ ene uene CO ~2 Coke*
Instantaneous Results 1 3.66 ~8.6 3.6 3.3 2.4 ~.9 0.8 0.0 48.4 3 3.47 43.6 4.0 3.8 2.3 2.7 0.9 0.0 42.7 2.07 43.5 4.4 3.9 2.1 107 Oq5 0.0 43.9 1.57 50.3 5.4 4.5 1.8 1.3 0.4 0.0 36.3 0.70 58.7 g.0 5.9 109 1.4 0.3 0.0 22.9 Cumulative Results 30 3.15 25~7 3.5 3.2 1.6 1.3 0.3 0.0 25.7 38,7 *Basis of instantaneous results i5 C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
Example 23 was repeated except that the contact zone temperature was 800C. Results are shown in Table XXVI below and are plotted as a func-tion of run time in Figure 14.
~47~
TABLE XXVI
% Selectivity*
Run %
Time Conver- Ben- Tol-(min.) sion C~H4 ~2~ C3 C4~ zene uene CO ~2 Coke*
Instantaneous Results 1 2.45 32.6 4.9 3.5 2.2 1.9 0~7 26.9 27.3 3 1 L 22 49.3 9.0 4.9 2.5 2.1 0.9 31.3 0.0 0.63 6~.3 20.3 7.2 3.0 2.5 0.7 0.~ 0.0 0.5~ 59.7 24.3 8.2 4.3 2.6 O.g 0.0 0.0 0.5~ 58.5 25.6 9.0 3.1 2.9 0.9 0.0 0.0 Cumulative Results 1.~5 38.6 12.9 4.6 2.1 1.8 0.7 4~0 1.6 33.7 *Basis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
An aqueous solution of antimony tartrate was added to Hourdy HSC 534 silica and allowed to stand for one hour. The mixture was dried at 110C for 4 hours and calcined at 700C for 16 hours. The relative amounts of antimony tartrate and silica were sufficient to yield a finished solid containing 5 wt.% Sb.
Finished solid (10 ml.) was charged to a quartz tube (0.5 in. inside diameter) surrounded by a tubular furnace. The reactor was brought up to 700C under a flow of nitrogen which was switched to methane at the start of the run. A feed of 100% methane was passed over the bed of solids. Contact zone temperaturek was 700C, the pressure was atmospheric, and the GHSV (gas hourly space velocity~
was 600 hrs.-l. Instantaneous samples were taken through-out the run and analyzed by gas chromatography and gas ~478~
chromatography-mass spectroscopy. A cumulative sample was also collected and analyzed. Results are reported in Table XXVII below. No carbon was detected on the solid at the end of the run. Figure 15 is a plot of methane conversion and % selectivity to C2~ hydrocarbon products vs. run time.
TABLE XXVII
Run Time % % Selectivity (min) _ conv. ~ 2~ C~ CO ~2 Instantaneous Results 100.5 1.2 5.6 6.2 0.3 35.552.3 1.0 0.6 2302 32.0 0.3 44.5 2.0 0.0~ 40.0 60.0 Cumulative Results -15 0.12 40.7 32.8 20.36.5 The reduced solid remaining at the end of the run described in Example 27 was regenerated under a flow of air at 700~C for 30 minutes. The reactor was flushed with nitrogen. The reoxidized solids were then contacted with 20 methane as in Example 27. Figure 16 is a plot of methane conversion vs. time for the combined results of Examples 17 and 28.
E_MPLE 29 Example 27 was repeated except that the contact zone temperature was 800~C. Results are shown in Table XXVIII below.
-- 4~ --7~
TABLE XXVIII
Run Time ~ % Selectivity (min) conv. ~ C2H~ C~ CO ~2 Instantaneous Results .5 2.7 10.3 11.7 .04 24.553.1 1.0 1.2 32.1 29.8 0.6 3~.1 2.0 0.5 55.6 4~.2 0.2 Cumulative Results 15 ~.25 ~4.2 3~.7 0.4 8.38.4 The supported oxides of bismuth employed in Examples 30-32 were made by impregnation of an aqueous solution of bismuth nitrate on Houdry HSC 534 silica, the amount of bismuth provided being sufficient to yield a solid containing 5 wt. % Bi/SiO2. The solids were dried at 100C for 4 hours and then calcined in air at 700C for 16 hours.
Runs described in Example 30-32 were made in a ~quartz tube reactor (12 mm. inside diameter) packed with 10 ml. of solids. Pressures were about atmospheric. The reactor was brought up to temperature under a flow of nitrogen which was switched to methane at the start of the run. Instantaneous samples of the effluent were taken throughout the runs and analyzed by gas chromatography and gas chromatography-mass spectroscropy. A cumulative sample was also collected and analyzed.
A feed of 100~ methane was passed over a bed of solids as described above. Contact zone temperature was 700C and the GHSV (gas hourly space velocity) was 600 hrs.~l. Results are reported in Table XXIX below. No _ ~,9 _ carbon was detected on the solid at the end of the run.
Figure 17 is a plot of methane conversion and ~ selectivity to C2~ hydrocarbon products vs. run time.
TABLE XXIX
__%_ electivity Run Time Conver-~min ? sion ~ C2HfiC3 C4-c7 CO ~2 Instantaneous Results ,5 3.40 8.89 22.19.22 .74 20.29 ~7.67 101 1.98 11.01 27.36.35 1.30 28.80 30.91 2 1.07 16~11 35.53O59 2.05 45.72 0 Cumulative Results 15 .38 30.13 46.151.503.35 14.62 4.2 The reduced solid remaining at the end of the run described in Example 30 was regenerated under a flow of air at 700C for 30 minutes. The reactor was flushed wi-th nitrogen. The reoxidized solids were then contacted with methane at a temperature of 700C and 600 hrs -1. Results are shown in Table XXX below. Figure 18 is a plot of methane conversion vs. time for the combined results of Examples 30 and 31.
~2~7~38 TABLE XXX
% Selectivity Run %
Time Conver-(min )sion C2H4 ~h C3 C4-c7 CO ~2 Instantaneous Results .5 2.27 5.6g 12.53.11 .31 35.66 45.70 1 1.19 12.14 24.63.30 .8~ 49.35 12.75 2 .37 29.55 67.461.021.98 0 0 Cumulative Results 15 .32 20.74 49.9210042.42 20.31 5.57 Example 30 was repeated except that the contact zone temperature was 800C. Results are shown in Table XXXI below.
TABLE XXXI
% Selectivity _ _ _ Run %
Time Conver-(min.)sion ~ C2H~ C3 C4-C7 - CO?
Instantaneous Results .5 29.6~ 7.71 6.68.14 .34 8.28 76.85 1 5.13 23.13 30.721.173.11 24.55 17.32 2 2.25 26.38 40.071.512.~9 29.04 0 Cumulative Results 15 1.04 30.05 44.842.152.28 15~71 4.97 ~1;)47~il A supported oxide of manganese was prepared by impre~nating the appropriate amount of manganese, as mangan-ous acetate in a water solution ! onto a Cab-O-Sil silica support. The impregnated solids were dried at 110C for 4 hours and then calcined in air a~ 700C for 16 hours. The composition of the calcined solids was 15 wt.% Mn/silica.
The finished solid was charged to a stainless steel tu~e (of 3/8 inch inside diameter) surrounded by a tubular furnace. The interior walls of the stainless steel tube had been treated with p~tassium pyrophospha~e to con~rol coke ~ormation cataly2ed by the reactor wall. The contact ~one t~mperature and pressure w~re raised to 700C
and 100 psig, r~spectively, under flôwing nitrogen.
Nitrogen flow was stopped and methane was introduced into the contact zone at a GHSV tgas hourly space velocity~ of 435 hrs.-l~ Reactor effluent was sampled at the reactor exit and analyzed on a gas chromatograph at a number of time interva}s~ In addition, all reactor effluent was 2Q collected in a sample bag for subsequent analysis of the cumulative reaction products. Results are reported in Table XXXII below. Figure 19 shows a plot of ~he ratio, ~ yield of C3~ hydrocarbon products/% yield of C2~ hydro-carbon products, vs. run time for the instantaneous results obtained in this run.
* Trade Mark ~2~9~7~1~
TABLE XXXII
% Selectivity Run %
Time Conver-~min.) sion ~ C~ C4-C7 CO ~2 Instantaneous Results -2 3~19 29.38 49.36 6.47 14.~0 0 0
7~
TABLE XVII
% Selectivity Run Time %
(min ) Conversion C~H~ C2H6 C3 ~2 Instantaneous Results 1 0.85 12.8 26.0 0.460.8 3 0.34 21.6 48.4 ~.629.4 6 0.21 31.3 6~.1 0.6 0.0 11 0.13 32.2 67.5 0.3 0.0 0.12 29.6 70.4 0.~ 0,0 Cumulative Results 30 0.25 29.1 50.4 0.3~0.2 The procedure of Example 16 was repeated except that the gas hourly space velocity was reduced to 86 hours~l. Results are shown in Table XVIII below, and a plot of methane conversion and selectivity to C2~ hydro-carbon products vs. run time is shown in Figure 8.
TABLE XVIII
% Selectivity Run Time 20 (min.) Conversion ~ h ~ 2 1 5.41 7.1 4.2 0.188.6 7 1.98 20.7 13.2 0.565.6 12 1.59 21.5 15.8 0.662.1 23 1.20 27.5 20.9 1.749.9 Cumulative Results -30 2.20 16.3 11.5 0.571.7 The procedure of Example 16 was repeated again except that the feed comprised 6 volume per cent methane in nitrogen. Results for the run are shown in Table XIX below.
~2~7~19 Figure 9 is a plot of methane conversion and selectivity to C2+ hydrocarbon products vs. run time.
TABLE XIX
% Selectivity Run Time %
(min.) Conversion C~H4 C2Hk C~ ~2 Instantaneous Results 1 5.6~ 0.8 0.9 0.0 98.3 5 0.32 15.3 31.3 0.2 53.2 12 0.27 12.5 33.~ 0.4 53.6 1029 0.17 13.1 36.1 0.0 50.8 Cumulative Results 30 0.49 10.4 25.6 0.1 63.9 Germanium dioxide (0.36 gram) was dissolved in 100 ml. water over a period of 12 hours. 1Ihis solution was added to 9.5 grams of Houdry HSC 534 silica and allowed to stand for 1 hour. The mixture was slowly taken to dryness with gentle warming, followed by heating at 110C. in a drying oven for 2 hours. The dried solid was then further heated to 700C. at a rate of 2/minute and held at 700C.
for 10 hours to give a product containing 2.5 weight %
germanium. The entire procedure was then repeated using the solid containing 2.5 weight % germanium instead of fresh silica, to give a final germanium oxide/silica solid containing 5 weight % germanium. The finished solid (2.6 grams) was charged to a quartz tube of 0.5 inch inside diameter surrounded by a tubular furnace. The reactor temperature was raised to 700C. under flowing nitrogen.
Nitrogen flow was stopped and methane was introduced into the reactor at a rate oE 100 ml./min. (860 hrs.~l GHSV).
-- ~10 --7~
The reactor effluent was sampled at the reactor exit and analyzed on a gas chromatograph at a number of time intervals. In addition, all reactor effluent was collected in a sample bag for subsequent analysis of the cumulative reaction products. Results (obtained at about atmospheric pressure and 700C.) are shown in Table XX below. The total amount of carbon oxides formed during reoxidation of the solids (see Example 21, infra) was used to calculate the yield of coke (or other carbonaceous deposit) formed on the solid during the methane run. The instantaneous results shown in Table XX are methane conversion to gaseous products and selectivity to these products (i.e~, % of C converted to gas phase products). The cumulative results shown in Table XX include solid ~ormation.
TABLE XX
% Selectivity*
Run Time Conver- Ben-(min.) sion C~H~ h _~ C~ zene CO Coke*
Instantaneous Results 201 0.39 10.4 26.0 1.0 0O3 0.0 62.3 3 0.18 41.3 49.6 5.8 2.5 0.8 0.0 10 0.15 53.3 33.3 6.7 4.7 2.0 0.0 30 0.13 54.2 27.2 11.4 5.4 1.8 0.0 Cumulative Results 30 0.22 31.9 25.2 6.4 3.2 1.4 6.~ 25.9 *Basis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
After completion of the run described in Example 20, the reactor was flushed with nitroyen for 30 minutes ~2~4~7W
and the solid was reoxidized under flowing air at 700C.
for 90 minutes. The reoxidized solid was then contacted with methane as described in Example 20. Results, shown in Table XXI below, are presented in the same manner as described in Example 20. Figure 10 is a plot of methane conversion to gaseous products ancl C2~ hydrocarbon select-ivity (basis: methane conversion to gaseous products) vs.
run time for the s~ombined results of Examples 20 and 21.
TABLE XII
~6 Selectivity*
Run %
Time Conver- Ben-(min.) sion ~L C~H,~ C3 C4,szene CO Coke*
_ . .
Instantaneous Results -~.30 6.8 20.5 0.7 0.3 0.071.7 3 0.19 37.6 5~.6 5.3 3.0 1.5 0.0 0.17 51.3 3201 9.0 5.1 2.5 0.0 0~14 56.4 2400 12.05.4 2.2 0.0 Cumulative Results 30 0.21 34.1 21.0 6.8 3.4 1.3 8.4 25.0 20 *Basis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
The procedure of Example 20 was repeated except that the methane run temperature was increased to 750C.
Results are shown in Table XXII below. Figure 11 shows the time dependence of methane conversion to all gaseous products and to gaseous hydrocarbons.
~97~38 TABLE XXII
% Selectivity*
Run %
Time Conver- Ben-(min.)sion C2H4 ~ C4,s zene CO Coke*
Instantaneous Results ~ 7 . . _ _ _ 1 1.41 38.6 24.6 3.5 2.5 1.9 2~.9 3 1.14 52.4 11.3 5O0 3.0 5.0 23.3 0.96 67.5 10.4 ~.6 4.2 7.2 ~.1 0.32 66.7 22.5 6.7 2.2 1.9 0.0 Cumulative Results 30 1.06 41.1 9.5 4.4 2.3 3.3 8.7 30.7 *Basis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
Lead (II) acetate ~0.92 gram) was dissolved in 100 ml. of water. This solution was added to 9.5 grams of Houdry HSC 534 silica and allowed to stand for one hour.
The mixture was slowly taken to dryness with gentle warming, followed by heating at 110C in a drying oven for 2 hours.
The solid was then heated to 500C at a rate of 2C/minute and held at 500C for 10 hours to give a finished solid containing 5 wt. % lead.
The finished solid (2.8 grams) was charged to a quartz tube (0.5 inch inside diameter) surrounded by a tubular furnace. The reactor temperature was raised to 700C under flowing nitrogen. Nitrogen flow was stopped and methane was introduced into the reactor at a rate of 100 ml./min. (860 hrs.-l G~SV). The reactor effluent was sampled at the reactor exit and analy~ed on a gas chromato-graph at a number of time intervals. In addition, all ~2~4~8~
reactor effluent was collected in a sample bag for subse~
quent analysis of the cumulative reaction products.
Results (obtained at about atmospheric pressure and 700C.) are shown in Table XXIII below. The total amount of carbon oxides formed during reoxidation of the solids (see Example 24, infra) was used to calculate the yield of coke (or other carbonaceous deposit) formed on the solid during the methane run. The instantaneous results shown in Table XXIII are methane conversion to gaseous products and 10 selectivity to these products (i.e., % of C converted to gas phase products). The cumulative results shown in Table XXIII include solid formation.
TABI.E XXIII
% Selectivity*
Run 96 Time Conver- Ben-(min.)sion ~2~ ~ C3 C~ zene CO ~2 Coke*
= .
Instantaneous Results 3.87 12.45.7 0,5 0.3 0.261.719.1 3 0.26 62.533.6 2.7 1.2 0.00.0 0.0 0.12 61.938.1 0.0 0.0 0.00.~ 0.0 0.08 58.341.7 0.0 0.0 0,00.0 0.0 0.08 57.542.5 0.0 0.0 0.00.0 0.0 Cumulative Results 30 0.33 23.1 14.9 0.3 0.2 0,124.07O5 29.9 *~asis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
9~20~7~3 After completion of the run described in Example 23, the reactor was flushed with nitrogen for 30 minutes and the solid was reoxidized under flowing air at 700C.
for 90 minutes. The reoxidized solid was then contacted with methane in the same manner described in Example 23.
Results, shown in Table XXIV below, are presented as in Example 23. Figure 12 as a plot o:E methane conversion to gaseous products and C2+ hydrocarbon product selectivity (basis: methane conversion to gaseous products) vs. run time for the combined results of Examples 23 and 24.
TABLE XXIV
% Selectivity*
.
Run %
Time Conver- Ben-~min.) sion ~2~ C2H~ C3 C4,s zene CO ~2 Coke*
Instantaneous Results 1 3.50 14.35.2 0.2 0.1 0.162.917.2 3 0.2g 54.143O9 1.0 0.7 0.30.0 0.0 0.16 51.24~.0 0.8 0.0 0.00.0 0.0 0.11 51.448.6 0.0 0.0 0.00.0 0,0 0.10 51.0~9.0 0.0 0.0 0.00.0 0.0 Cumulative Results 30 0.31 25.3 23.1 0.5 0.3 0.119.2 7.4 25.0 *Basis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
Example 23 was repeated except that the GHSV was 86 hrs.~l, Results are shown in Table XXV below and are plotted as a function of run time in Figure 13.
- ~5 -TABLE XXV
% Selectivity*
Run Time Conver-Ben- Tol-(min.) sion ~2~ C2H6 C3 ~ ene uene CO ~2 Coke*
Instantaneous Results 1 3.66 ~8.6 3.6 3.3 2.4 ~.9 0.8 0.0 48.4 3 3.47 43.6 4.0 3.8 2.3 2.7 0.9 0.0 42.7 2.07 43.5 4.4 3.9 2.1 107 Oq5 0.0 43.9 1.57 50.3 5.4 4.5 1.8 1.3 0.4 0.0 36.3 0.70 58.7 g.0 5.9 109 1.4 0.3 0.0 22.9 Cumulative Results 30 3.15 25~7 3.5 3.2 1.6 1.3 0.3 0.0 25.7 38,7 *Basis of instantaneous results i5 C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
Example 23 was repeated except that the contact zone temperature was 800C. Results are shown in Table XXVI below and are plotted as a func-tion of run time in Figure 14.
~47~
TABLE XXVI
% Selectivity*
Run %
Time Conver- Ben- Tol-(min.) sion C~H4 ~2~ C3 C4~ zene uene CO ~2 Coke*
Instantaneous Results 1 2.45 32.6 4.9 3.5 2.2 1.9 0~7 26.9 27.3 3 1 L 22 49.3 9.0 4.9 2.5 2.1 0.9 31.3 0.0 0.63 6~.3 20.3 7.2 3.0 2.5 0.7 0.~ 0.0 0.5~ 59.7 24.3 8.2 4.3 2.6 O.g 0.0 0.0 0.5~ 58.5 25.6 9.0 3.1 2.9 0.9 0.0 0.0 Cumulative Results 1.~5 38.6 12.9 4.6 2.1 1.8 0.7 4~0 1.6 33.7 *Basis of instantaneous results is C converted to gas phase products and does not include conversion to solid, carbonaceous deposits.
An aqueous solution of antimony tartrate was added to Hourdy HSC 534 silica and allowed to stand for one hour. The mixture was dried at 110C for 4 hours and calcined at 700C for 16 hours. The relative amounts of antimony tartrate and silica were sufficient to yield a finished solid containing 5 wt.% Sb.
Finished solid (10 ml.) was charged to a quartz tube (0.5 in. inside diameter) surrounded by a tubular furnace. The reactor was brought up to 700C under a flow of nitrogen which was switched to methane at the start of the run. A feed of 100% methane was passed over the bed of solids. Contact zone temperaturek was 700C, the pressure was atmospheric, and the GHSV (gas hourly space velocity~
was 600 hrs.-l. Instantaneous samples were taken through-out the run and analyzed by gas chromatography and gas ~478~
chromatography-mass spectroscopy. A cumulative sample was also collected and analyzed. Results are reported in Table XXVII below. No carbon was detected on the solid at the end of the run. Figure 15 is a plot of methane conversion and % selectivity to C2~ hydrocarbon products vs. run time.
TABLE XXVII
Run Time % % Selectivity (min) _ conv. ~ 2~ C~ CO ~2 Instantaneous Results 100.5 1.2 5.6 6.2 0.3 35.552.3 1.0 0.6 2302 32.0 0.3 44.5 2.0 0.0~ 40.0 60.0 Cumulative Results -15 0.12 40.7 32.8 20.36.5 The reduced solid remaining at the end of the run described in Example 27 was regenerated under a flow of air at 700~C for 30 minutes. The reactor was flushed with nitrogen. The reoxidized solids were then contacted with 20 methane as in Example 27. Figure 16 is a plot of methane conversion vs. time for the combined results of Examples 17 and 28.
E_MPLE 29 Example 27 was repeated except that the contact zone temperature was 800~C. Results are shown in Table XXVIII below.
-- 4~ --7~
TABLE XXVIII
Run Time ~ % Selectivity (min) conv. ~ C2H~ C~ CO ~2 Instantaneous Results .5 2.7 10.3 11.7 .04 24.553.1 1.0 1.2 32.1 29.8 0.6 3~.1 2.0 0.5 55.6 4~.2 0.2 Cumulative Results 15 ~.25 ~4.2 3~.7 0.4 8.38.4 The supported oxides of bismuth employed in Examples 30-32 were made by impregnation of an aqueous solution of bismuth nitrate on Houdry HSC 534 silica, the amount of bismuth provided being sufficient to yield a solid containing 5 wt. % Bi/SiO2. The solids were dried at 100C for 4 hours and then calcined in air at 700C for 16 hours.
Runs described in Example 30-32 were made in a ~quartz tube reactor (12 mm. inside diameter) packed with 10 ml. of solids. Pressures were about atmospheric. The reactor was brought up to temperature under a flow of nitrogen which was switched to methane at the start of the run. Instantaneous samples of the effluent were taken throughout the runs and analyzed by gas chromatography and gas chromatography-mass spectroscropy. A cumulative sample was also collected and analyzed.
A feed of 100~ methane was passed over a bed of solids as described above. Contact zone temperature was 700C and the GHSV (gas hourly space velocity) was 600 hrs.~l. Results are reported in Table XXIX below. No _ ~,9 _ carbon was detected on the solid at the end of the run.
Figure 17 is a plot of methane conversion and ~ selectivity to C2~ hydrocarbon products vs. run time.
TABLE XXIX
__%_ electivity Run Time Conver-~min ? sion ~ C2HfiC3 C4-c7 CO ~2 Instantaneous Results ,5 3.40 8.89 22.19.22 .74 20.29 ~7.67 101 1.98 11.01 27.36.35 1.30 28.80 30.91 2 1.07 16~11 35.53O59 2.05 45.72 0 Cumulative Results 15 .38 30.13 46.151.503.35 14.62 4.2 The reduced solid remaining at the end of the run described in Example 30 was regenerated under a flow of air at 700C for 30 minutes. The reactor was flushed wi-th nitrogen. The reoxidized solids were then contacted with methane at a temperature of 700C and 600 hrs -1. Results are shown in Table XXX below. Figure 18 is a plot of methane conversion vs. time for the combined results of Examples 30 and 31.
~2~7~38 TABLE XXX
% Selectivity Run %
Time Conver-(min )sion C2H4 ~h C3 C4-c7 CO ~2 Instantaneous Results .5 2.27 5.6g 12.53.11 .31 35.66 45.70 1 1.19 12.14 24.63.30 .8~ 49.35 12.75 2 .37 29.55 67.461.021.98 0 0 Cumulative Results 15 .32 20.74 49.9210042.42 20.31 5.57 Example 30 was repeated except that the contact zone temperature was 800C. Results are shown in Table XXXI below.
TABLE XXXI
% Selectivity _ _ _ Run %
Time Conver-(min.)sion ~ C2H~ C3 C4-C7 - CO?
Instantaneous Results .5 29.6~ 7.71 6.68.14 .34 8.28 76.85 1 5.13 23.13 30.721.173.11 24.55 17.32 2 2.25 26.38 40.071.512.~9 29.04 0 Cumulative Results 15 1.04 30.05 44.842.152.28 15~71 4.97 ~1;)47~il A supported oxide of manganese was prepared by impre~nating the appropriate amount of manganese, as mangan-ous acetate in a water solution ! onto a Cab-O-Sil silica support. The impregnated solids were dried at 110C for 4 hours and then calcined in air a~ 700C for 16 hours. The composition of the calcined solids was 15 wt.% Mn/silica.
The finished solid was charged to a stainless steel tu~e (of 3/8 inch inside diameter) surrounded by a tubular furnace. The interior walls of the stainless steel tube had been treated with p~tassium pyrophospha~e to con~rol coke ~ormation cataly2ed by the reactor wall. The contact ~one t~mperature and pressure w~re raised to 700C
and 100 psig, r~spectively, under flôwing nitrogen.
Nitrogen flow was stopped and methane was introduced into the contact zone at a GHSV tgas hourly space velocity~ of 435 hrs.-l~ Reactor effluent was sampled at the reactor exit and analyzed on a gas chromatograph at a number of time interva}s~ In addition, all reactor effluent was 2Q collected in a sample bag for subsequent analysis of the cumulative reaction products. Results are reported in Table XXXII below. Figure 19 shows a plot of ~he ratio, ~ yield of C3~ hydrocarbon products/% yield of C2~ hydro-carbon products, vs. run time for the instantaneous results obtained in this run.
* Trade Mark ~2~9~7~1~
TABLE XXXII
% Selectivity Run %
Time Conver-~min.) sion ~ C~ C4-C7 CO ~2 Instantaneous Results -2 3~19 29.38 49.36 6.47 14.~0 0 0
4 10.44 15.57 10.17 1.84 1.56 2.75 68.11 8 2.62 6.45 18.65 1.54 0.89 13.98 58.49 16 1.23 Q 78.80 ~.73 1.55 14.93 0 Cumulative Results 30 2.~7 3.78 35.22 3.431.86 34.14 21.57 The procedure of Example 33 was repeated except that the methane feed rate was increased to provide a GHSV
of 2392 hrs.-l. Figure 19 shows a plot of the ratio, %
yield of C3+ hydrocarbon products/~ yield of C2+ hydro-carbon products vs. run time for the instantaneous results obtained in this run.
COMPARATIVE EXAMPLE A
..
The procedure of Example 33 was repeated exc~pt that the pressure in the contact zone during the methane run was 0 psig. Figure 19 shows a plot of the ratio, % yield of C3+ hydrocarbon products/% yield of C2+ hydrocarbon pro-ducts, vs~ run time for the results obtained in this run.
Following the same preparative procedure described in Example 31, a composition containing 5 wt.% Mn/SiO2 was prepared and contacted with methane (as described in Example 33) under the operating conditions shown in Table XXXIII
below. Table XXXIII also shows instantaneous results 7~
(i.e., % methane conversion and % selectivity to C3+ hydro-carbon products) obtained at 2.0 and 1.0 minutes, respec-tivel~, in Examples 35 and 36.
A supported oxide of indium was prepared by impregnating the appropriate amount oE indium, as indium nitrate in a water solution, onto a silica support. The impregnated solids were dried at 110C for 2 hours. The dried solid was then heated to 700C at 2/minute and held at 700C for 10 hours in air to give a finished solid containing 5 wt.% In. This solid was contacted with methane as described in Example 33 under the operating conditions shown in Table XXXIII below. Table XXXIII also show instantaneous results obtained at 2.0 minutes after the start of ~he methane contact.
COMPARATIVE EXAMPLE B
Methane was contacted, at atmospheric pressure, with a bed of 5 wt.% Mn/SiO2 (prepared as described in Example 33) in a quartz tube reactor (12 mm. inside diame~er) packed with 10 ml. of the solid. The temperature in the contact zone was maintained at 700C and the GHSV
was 600 hrs.~l. Instantaneous results obtained at a run time of 2 minutes are shown in Table XXXIII below.
COMPAR~TIVE EXAMPLE C
Methane was contacted, at atmospheric pressure, with a bed of 5 wt.% In/SiO2 (prepared as described in Example 5) in a quartz tube reactor (0.5 inch inside dia-meter) packed with 2.7 grams of the solid. The temperature in the contact zone was maintained at 700C and the G~SV
was 860 hrs.~l. Instantaneous results obtained at run time of 1.0 and 3.0 minutes are shown in Table XXXIII below.
of 2392 hrs.-l. Figure 19 shows a plot of the ratio, %
yield of C3+ hydrocarbon products/~ yield of C2+ hydro-carbon products vs. run time for the instantaneous results obtained in this run.
COMPARATIVE EXAMPLE A
..
The procedure of Example 33 was repeated exc~pt that the pressure in the contact zone during the methane run was 0 psig. Figure 19 shows a plot of the ratio, % yield of C3+ hydrocarbon products/% yield of C2+ hydrocarbon pro-ducts, vs~ run time for the results obtained in this run.
Following the same preparative procedure described in Example 31, a composition containing 5 wt.% Mn/SiO2 was prepared and contacted with methane (as described in Example 33) under the operating conditions shown in Table XXXIII
below. Table XXXIII also shows instantaneous results 7~
(i.e., % methane conversion and % selectivity to C3+ hydro-carbon products) obtained at 2.0 and 1.0 minutes, respec-tivel~, in Examples 35 and 36.
A supported oxide of indium was prepared by impregnating the appropriate amount oE indium, as indium nitrate in a water solution, onto a silica support. The impregnated solids were dried at 110C for 2 hours. The dried solid was then heated to 700C at 2/minute and held at 700C for 10 hours in air to give a finished solid containing 5 wt.% In. This solid was contacted with methane as described in Example 33 under the operating conditions shown in Table XXXIII below. Table XXXIII also show instantaneous results obtained at 2.0 minutes after the start of ~he methane contact.
COMPARATIVE EXAMPLE B
Methane was contacted, at atmospheric pressure, with a bed of 5 wt.% Mn/SiO2 (prepared as described in Example 33) in a quartz tube reactor (12 mm. inside diame~er) packed with 10 ml. of the solid. The temperature in the contact zone was maintained at 700C and the GHSV
was 600 hrs.~l. Instantaneous results obtained at a run time of 2 minutes are shown in Table XXXIII below.
COMPAR~TIVE EXAMPLE C
Methane was contacted, at atmospheric pressure, with a bed of 5 wt.% In/SiO2 (prepared as described in Example 5) in a quartz tube reactor (0.5 inch inside dia-meter) packed with 2.7 grams of the solid. The temperature in the contact zone was maintained at 700C and the G~SV
was 860 hrs.~l. Instantaneous results obtained at run time of 1.0 and 3.0 minutes are shown in Table XXXIII below.
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Claims (66)
1. A method for converting methane to higher hydrocarbon products which comprises contacting a gas comprising methane and an oxidative synthesizing agent comprising a reducible oxide of at least one metal selected from the group consisting of manganese, tin, indium, germanium, lead, antimony, and bismuth at a temperature selected within the range of about 500 to 1000°C, provided that when said oxidative synthesizing agent comprises a reducible oxide of manganese or indium, said contacting is carried out in the substantial absence of catalytically effective Ni, Rh, Pd, Ag, Os, Ir, Pt, Au and compounds thereof.
2. The method of Claim 1 wherein the gas contains about 40 to 100 vol. % methane.
3. The method of Claim 1 wherein the gas contains about 80 to 100 vol. % methane.
4. The method of Claim 1 wherein the gas contains about 90 to 100 vol. % methane.
5. The method of Claim 1 wherein the gas compri-sing methane is natural gas.
6. The method of Claim 1 wherein the gas compri-sing methane is processed natural gas.
7. The method of Claim 1 wherein a gas consis-ting essentially of methane is contacted with the said reducible oxide.
8. A method for synthesizing hydrocarbons from a methane source which comprises:
(a) contacting a gas comprising methane with a solid comprising a reducible oxide of at least one metal selected from the group consisting of manganese, tin, indium, germanium, lead, antimony and bismuth at a temperature selected within the range of about 500 to 1000°C to form C2+ hydrocarbons, coproduct water and solids comprising a reduced metal oxide, provided that when said solid comprises a reducible oxide of manganese or indium, said contacting is carried out in the substantial absence of catalytically effective Ni, Rh, Pd, Ag, Os, Ir, Pt, Au and compounds thereof;
(b) recovering C2+ hydrocarbons;
(c) at least periodically contacting the solids comprising a reduced metal oxide with an oxygen-containing gas to produce solid comprising a reducible metal oxide; and (d) contacting a gas comprising methane with the solids produced in step (c) as recited in step (a).
(a) contacting a gas comprising methane with a solid comprising a reducible oxide of at least one metal selected from the group consisting of manganese, tin, indium, germanium, lead, antimony and bismuth at a temperature selected within the range of about 500 to 1000°C to form C2+ hydrocarbons, coproduct water and solids comprising a reduced metal oxide, provided that when said solid comprises a reducible oxide of manganese or indium, said contacting is carried out in the substantial absence of catalytically effective Ni, Rh, Pd, Ag, Os, Ir, Pt, Au and compounds thereof;
(b) recovering C2+ hydrocarbons;
(c) at least periodically contacting the solids comprising a reduced metal oxide with an oxygen-containing gas to produce solid comprising a reducible metal oxide; and (d) contacting a gas comprising methane with the solids produced in step (c) as recited in step (a).
9. The method of Claim 8 wherein the temperature of step (c) is selected within the range of about 300 to 1200°C.
10. A method for converting methane to higher hydrocarbon products which comprises contacting a gas comprising methane and a reducible oxide of manganese at a temperature within the range of about 500 to 1000°C, said contacting being carried out in the substantial absence of catalytically effective Ni, Rh, Pd, Ag, Os, In, Pt, Au and compounds thereof.
11. The method of Claim 10 wherein the reducible oxide of manganese is contacted with a gas comprising methane at a temperature within the range of about 600 to 900°C.
12. The method of Claim 10 wherein the gas contains about 40 to 100 vol. % methane.
13. The method of Claim 10 wherein the gas contains about 80 to 100 vol. % methane.
14. The method of Claim 10 wherein the gas contains about 90 to 100 vol. % methane.
15. The method of Claim 10 wherein the gas comprising methane is natural gas.
16. The method of Claim 10 wherein the gas comprising methane is processed natural gas.
17. The method of Claim 10 wherein a gas consis-ting essentially of methane is contacted with the said reducible oxide.
18. The method of Claim 10 wherein the reducible oxide of manganese comprises Mn3O4.
19. The method of Claim 10 wherein the oxide of manganese is associated with a support material.
20. The method of Claim 18 wherein the oxide of manganese is associated with a support material.
21. The method of Claim 19 wherein the support material is silica.
22. The method of Claim 20 wherein the support material is silica.
23. A method for synthesizing hydrocarbons from a methane source which comprises:
(a) contacting a gas comprising methane with a solid comprising a reducible oxide of manganese at a temperature within the range of about 500 to 1000°C to form C2+
hydrocarbons, coproduct water, and solids comprising a reduced oxide of manganese, said contacting being carried out in the substantial absence of catalyt-ically effective Ni, Rh, Pd, Ag, Os, Ir, Pt, Au and compounds thereof;
(b) recovering C2+ hydrocarbons;
(c) at least periodically contacting the solids comprising the reduced oxide of manganese with an oxygen containing gas to produce a solid comprising a reducible oxide of manganese; and (d) contacting a gas comprising methane with the solids produced in step (c) as recited in step (a).
(a) contacting a gas comprising methane with a solid comprising a reducible oxide of manganese at a temperature within the range of about 500 to 1000°C to form C2+
hydrocarbons, coproduct water, and solids comprising a reduced oxide of manganese, said contacting being carried out in the substantial absence of catalyt-ically effective Ni, Rh, Pd, Ag, Os, Ir, Pt, Au and compounds thereof;
(b) recovering C2+ hydrocarbons;
(c) at least periodically contacting the solids comprising the reduced oxide of manganese with an oxygen containing gas to produce a solid comprising a reducible oxide of manganese; and (d) contacting a gas comprising methane with the solids produced in step (c) as recited in step (a).
24. The method of Claim 23 wherein the temperature of step (c) is within the range of about 300 to 1200°C.
25. The method of Claim 23 wherein the tempera-ture of step (c) is within the range of about 700 to 1200°C.
26. The method of Claim 23 wherein the tempera-ture of step (c) is within the range from about 900 to 1200°C.
27. The method of Claim 26 wherein the reducible oxide of manganese comprises Mn3O4.
28. The method of Claim 25 wherein the said solid of step (a) comprises Mn3O4 on a silica support.
29. The method of Claim 23 wherein the tempera-ture of step (a) is within the range of about 600 to 900°C.
30. The method of Claim 29 wherein the tempera-ture of step (c) is within the range of about 700 to 1200°C.
31. A method for converting methane to higher hydrocarbon products which comprises contacting a gas comprising methane and a reducible oxide of tin at a temperature within the range of about 500 to 1000°C.
32. A method for converting methane to higher hydrocarbon products which comprises contacting a gas comprising methane and a reducible oxide of indium at a temperature within the range of about 500 to 850°C, said contacting being carried out in the substantial absence of catalytically effective Ni, Rh, Pd, Ag, Os, Ir, Pt, Au and compounds thereof.
33. A method for converting methane to higher hydrocarbon products which comprises contacting a gas comprising methane and a reducible oxide of germanium at a temperature within the range of about 500 to 800°C.
34. A method for converting methane to higher hydrocarbon products which comprises contacting a gas comprising methane and a reducible oxide of lead at a temperature within the range of about 500 to 1000°C.
35. A method for converting methane to higher hydrocarbon products which comprises contacting a gas comprising methane and a reducible oxide of antimony at a temperature within the range of about 500 to 1000°C.
36. A method for converting methane to higher hydrocarbon products which comprises contacting a gas comprising methane and a reducible oxide of bismuth at a temperature within the range of about 500 to 850°C.
37. A method for converting methane to higher hydrocarbon products by contacting methane with an oxida-tive synthesizing agent which agent comprises at least one reducible oxide of at least one metal which oxides when contacted with methane at synthesizing conditions are reduced and produce higher hydrocarbon products and water;
which method comprises contacting a gas comprising methane and an oxidative synthesizing agent under elevated pressure.
which method comprises contacting a gas comprising methane and an oxidative synthesizing agent under elevated pressure.
38. The method of claim 37 wherein the pressure is within the range of about 2 to 100 atmospheres.
39. The method of claim 37 wherein the pressure is within the range of about 3 to 30 atmospheres.
40. A method for converting methane to higher hydrocarbon products by contacting methane with an oxida-tive synthesizing agent comprising at least one reducible oxide of at least one metal selected from the group consis-ting of Mn, Sn, In, Ge, Pb, Sb and Bi, which method comprises contacting a gas comprising methane and said oxidative synthesizing agent under elevated pressure.
41. The method of Claim 40 wherein the pressure is within the range of about 2 to 100 atmospheres.
42. The method of Claim 40 wherein the pressure is within the range of about 3 to 30 atmospheres.
43. The method of Claim 41 wherein the tempera-ture of said contact is selected within the range of about 500 to 1000°C.
44. The method of Claim 43 wherein the metal selected is Mn.
45. The method of Claim 44 wherein the said contacting is carried out in the substantial absence of catalytically effective Ni, Rh, Pd, Ag, Os, Ir, Pt, Au and compounds thereof.
46, A method for converting methane to higher hydrocarbon products by contacting methane with an oxida-tive synthesizing agent which agent comprises at least one reducible oxide of at least one metal which oxides when contacted with methane under synthesizing conditions are reduced and produce higher hydrocarbon products and water;
which method comprises:
(a) continuously introducing and contacting a gas comprising methane and particles comprising an oxidative synthesizing agent under synthesizing conditions in a first contact zone to form C2+ hydro-carbons, coproduct water, and particles comprising a reduced metal oxide;
(b) continuously removing particles compri-sing a reduced metal oxide from the first zone and contacting the particles with an oxygen-containing gas in a second zone to produce particles compri-sing an oxidative synthesizing agent;
and (c) returning particles formed in the second zone to the first zone.
which method comprises:
(a) continuously introducing and contacting a gas comprising methane and particles comprising an oxidative synthesizing agent under synthesizing conditions in a first contact zone to form C2+ hydro-carbons, coproduct water, and particles comprising a reduced metal oxide;
(b) continuously removing particles compri-sing a reduced metal oxide from the first zone and contacting the particles with an oxygen-containing gas in a second zone to produce particles compri-sing an oxidative synthesizing agent;
and (c) returning particles formed in the second zone to the first zone.
47. A method for converting methane to higher hydrocarbon products which comprises:
(a) continuously introducing and contacting a gas comprising methane and particles comprising an oxidative synthesizing agent, which agent comprises at least one reducible oxide of at least one metal selected from the group consisting of Mn, Sn, In, Ge, Pb, Sb and Bi, under synthesis conditions in a first contact zone to form C2+ hydrocarbons, coproduct water, and particles comprising reduced synthesizing agent; and (b) continuously removing particles compri-sing reduced synthesizing agent from the first zone and contacting the said reduced particles with an oxygen-containing gas in a second zone to produce particles comprising an oxida-tive synthesizing agent; and (c) returning particles formed in the second zone to the first zone.
(a) continuously introducing and contacting a gas comprising methane and particles comprising an oxidative synthesizing agent, which agent comprises at least one reducible oxide of at least one metal selected from the group consisting of Mn, Sn, In, Ge, Pb, Sb and Bi, under synthesis conditions in a first contact zone to form C2+ hydrocarbons, coproduct water, and particles comprising reduced synthesizing agent; and (b) continuously removing particles compri-sing reduced synthesizing agent from the first zone and contacting the said reduced particles with an oxygen-containing gas in a second zone to produce particles comprising an oxida-tive synthesizing agent; and (c) returning particles formed in the second zone to the first zone.
48. The method of Claim 47 wherein particles are maintained in the first zone as a fluidized bed of solids.
49. The method of Claim 48 wherein particles are maintained in the first zone as a fluidized bed of solids.
50. The method of Claim 48 wherein the average residence time of particles in the first zone is within the range of about 0.04 to 30 minutes.
51. The method of Claim 48 wherein the average residence time of particles in the first zone is within the range of about 0.04 to 4 minutes.
52. The method of Claim 50 wherein the residence time of methane feedstock in the first zone is within the range of about 0.1 to 100 seconds.
53. The method of Claim 50 wherein the residence time of methane feedstock in the first zone is within the range of about 1 to 20 seconds.
54. The method of Claim 47 wherein the tempera-ture of the first zone is selected within the range of about 500 to 1000°C.
55. The method of Claim 47 wherein the said reducible oxide is associated with a support material.
56. The method of Claim 55 wherein the support material is silica.
57. The method of Claim 47 wherein the metal selected is Mn.
58. The method of Claim 57 wherein said contact-ing in the first zone is carried out in the substantial absence of catalytically effective Ni, Rh, Pd, Ag, Os Ir, Pt, Au and compounds thereof.
59. The method of Claim 57 wherein the tempera-ture of the first zone is within the range of about 500 to 1000°C.
60. The method of Claim 47 wherein the metal selected is Sn and the temperature of the first zone is within the range of about 500 to 1000°C.
61. The method of Claim 47 wherein the metal selected is In and the temperature of the first zone is within the range of about 500 to 850°C.
62. The method of Claim 61 wherein the contact-ing in the first zone is carried out in the substantial absence of catalytically effective Ni, Rh, Pd, Ag, Os, Ir, Pt, Au and compounds thereof.
63. The method of Claim 47 wherein the metal selected is Ge and the temperature of the first zone is within the range of about 500 to 800°C.
64. The method of Claim 47 wherein the metal selected is Pb and the temperature of the first zone is within the range of about 500 to 1000°C.
65. The method of Claim 47 wherein the metal selected is Sb and the temperature of the first zone is within the range of about 500 to 1000°C.
66. The method of Claim 47 wherein the metal selected is Bi and the temperature of the first zone is within the range of about 500 to 850°C.
Applications Claiming Priority (36)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US41266282A | 1982-08-30 | 1982-08-30 | |
| US41266382A | 1982-08-30 | 1982-08-30 | |
| US41266782A | 1982-08-30 | 1982-08-30 | |
| US41266682A | 1982-08-30 | 1982-08-30 | |
| US41265082A | 1982-08-30 | 1982-08-30 | |
| US41265582A | 1982-08-30 | 1982-08-30 | |
| US41266482A | 1982-08-30 | 1982-08-30 | |
| US41264982A | 1982-08-30 | 1982-08-30 | |
| US41266582A | 1982-08-30 | 1982-08-30 | |
| US412,649 | 1982-08-30 | ||
| US412,662 | 1982-08-30 | ||
| US412,664 | 1982-08-30 | ||
| US412,667 | 1982-08-30 | ||
| US412,663 | 1982-08-30 | ||
| US412,655 | 1982-08-30 | ||
| US412,666 | 1982-08-30 | ||
| US412,650 | 1982-08-30 | ||
| US412,665 | 1982-08-30 | ||
| US06/522,942 US4443648A (en) | 1982-08-30 | 1983-08-12 | Methane conversion |
| US522,935 | 1983-08-12 | ||
| US522,944 | 1983-08-12 | ||
| US06/522,876 US4443644A (en) | 1982-08-30 | 1983-08-12 | Methane conversion |
| US06/522,938 US4560821A (en) | 1982-08-30 | 1983-08-12 | Methane conversion |
| US522,906 | 1983-08-12 | ||
| US522,925 | 1983-08-12 | ||
| US522,942 | 1983-08-12 | ||
| US06/522,877 US4443647A (en) | 1982-08-30 | 1983-08-12 | Methane conversion |
| US06/522,906 US4443646A (en) | 1982-08-30 | 1983-08-12 | Methane conversion |
| US522,876 | 1983-08-12 | ||
| US06/522,944 US4444984A (en) | 1982-08-30 | 1983-08-12 | Methane conversion |
| US06/522,905 US4443645A (en) | 1982-08-30 | 1983-08-12 | Methane conversion |
| US522,905 | 1983-08-12 | ||
| US06/522,925 US4443649A (en) | 1982-08-30 | 1983-08-12 | Methane conversion |
| US06/522,935 US4554395A (en) | 1982-08-30 | 1983-08-12 | Methane conversion |
| US522,877 | 1983-08-12 | ||
| US522,938 | 1983-08-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1204788A true CA1204788A (en) | 1986-05-20 |
Family
ID=27586209
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000435442A Expired CA1204788A (en) | 1982-08-30 | 1983-08-26 | Methane conversion |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1204788A (en) |
-
1983
- 1983-08-26 CA CA000435442A patent/CA1204788A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 20030826 |