BRPI0621924A2 - process for removing oxygenated compounds from a stream - Google Patents

Abstract

PROCESS FOR REMOVING OXYGEN COMPOUNDS FROM A CHAIN The present invention comprises a process for removing oxygenated compounds from a paraffin-rich or olefin-rich stream, which comprises passing a feed stream comprising one or more C ~ 10 ~ feed paraffins. the C ~ 15 or olefin-rich paraffin stream and one or more oxygenated compounds through an adsorbent bed comprising one or more adsorbents selected from silica gel, activated alumina and sodium zeolites to remove essentially all said oxygenated compound; and recovering said paraffins. A second adsorbent bed can be employed to remove these oxygenated compounds more completely.

Description

"PROCESS FOR REMOVING OXYGENIZED COMPOUNDS FROM A CURRENT"

BACKGROUND OF THE INVENTION

The invention relates to a process for removing oxygenated paraffin compounds or paraffin and olefin mixture. The invention is in particular used for the removal of oxygenated compounds from C10 to C15 paraffins or a mixture of paraffins and olefins prior to the use of these paraffins or olefins or mixtures thereof in further processes or reactions.

There are numerous industrial applications for paraffins or olefins or mixtures thereof in the range of C10 to C15. Among these uses are as a precursor to straight alkylbenzene benzene (LAB) which is used to produce straight alkylbenzene sulfonate (LAS) 5 the flagship surfactant of the detergent industry. These paraffins or olefins or mixtures thereof may also be used as precursors to be upgraded to higher value fuels. As concerns about pollution from traditional fossil fuels increase and crude oil sources decline, there is greater interest in other energy sources. A promising source of energy is the synthetic production of fuels, lubricants and other natural gas or coal products. The gas-to-fuel process is often referred to as gas-to-liquids or GTL and is often prepared by the Fischer-Tropsch process. See, for example, US 4,973,453, which is incorporated herein by reference. Paraffins and straight olefins in the range of C10 to C15 are of particular value with respect to these processes.

Synthetic hydrocarbon production by catalytic synthesis gas reaction is well known and is generally referred to as the Fischer-Tropsch reaction. The Fischer-Tropsch process was developed in the late 20th century in Germany. It was practiced commercially in Germany during World War II and was later practiced in South Africa.

Synthesis gas (mainly hydrogen and carbon monoxide) is produced from coal or natural gas (methane). Then the synthesis gas is converted to liquid hydrocarbons. Fischer-Tropsch reaction to convert synthesis gas was characterized in some examples by the following general reaction:

2H2 + CO charalizer -CH2 + H2O

Hydrocarbon products derived from the Fischer-Tropsch reaction range from some methane to high molecular weight paraffin waxes containing more than 50 carbon atoms.

Numerous catalysts that incorporate active metals, such as iron, cobalt, ruthenium, rhenium, etc., have been used to carry out the reaction and both saturated and unsaturated hydrocarbons can be produced. The synthesis reaction is very exothermic and temperature sensitive at which temperature control is required to maintain a desired hydrocarbon product selectivity.

Synthesis gas used in the Fischer-Tropsch reaction can be prepared from natural gas, carbonated coal and other sources. Numerous basic methods have been employed to produce the synthesis gas ("singás") used as a feedstock in the Fischer-Tropsch reaction. The numerous methodologies and systems that have been used to prepare synthesis gas include partial oxidation, steam reforming, self-reformation or self-thermal reformation. Both fixed and fluid bed systems were employed.

Reform reactions are endothermic and a nickel-containing catalyst is often used. Partial (non-catalytic or catalytic) oxidation involves sub-stoichiometric combustion of light hydrocarbons such as methane to produce the synthesis gas. The partial oxidation reaction is typically performed commercially using high purity oxygen.

In some situations these synthesis gas production methods may be combined to form another method. A combination of partial oxidation and vapor reforming, known as auto-thermal reforming, in which air can be used as the oxygen-containing gas for the partial oxidation reaction, has also been used to produce synthesis gas. Auto-thermal reforming, the combination of partial oxidation and steam reforming, allows the exothermic heat from partial oxidation to provide the heat needed for the endothermic steam reforming reaction. The self-heat reforming process may be carried out in a relatively inexpensive refractory aligned carbon steel vessel in which a relatively lower cost is typically involved.

The Fischer-Tropsch process for producing paraffins and paraffin / olefin mixtures also produces a wide variety of oxygenated compounds. These oxygenated compounds, which include aldehydes, acids, ketones and alcohols, are harmful in a variety of applications of these paraffins or olefins or mixtures thereof. In particular, catalysts used to further process the paraffins and paraffin / olefin mixture to their desired end product are poisoned by oxygenated compounds. The oxygenate content needs to be reduced by amounts in the range of 200 to 400 parts per million in an untreated paraffin / and (or) olefin stream below up to 1 part per million or less so that paraffins or olefins or mixtures thereof are processed without poisoning the adsorbent / catalyst or otherwise being detrimental to the processing of these paraffins or olefins or mixtures thereof.

There are several different adsorption schemes proposed for the removal of oxygenated compounds from low carbon paraffins, ie those with an average C5. For example, in US 6,111,162, hydrocarbons having 3 to 8 carbon atoms were treated by the removal of oxygenated contaminants by an adsorbent comprising silica gel. In US 5,427,689, a variety of polar substances including water, alcohols, ethers, aldehydes, ketones, amines, mercaptans, organic sulfites and carboxylic acids have been removed from a hydrocarbon containing 10 10 carbon atoms using a sorbent composition comprising aluminum borate. and zirconium borate. US 4,404,118 provides for the removal of oxygenated compounds from a stream comprising C4 hydrocarbons. However, so far, a process has not been proposed to sufficiently remove oxygenated compounds from the high carbon (C10 to C15) paraffins and paraffin / olefin mixture employed in the process of the present invention. These mixtures comprise from 0 to 50 wt% olefins and 50 to 99.99 wt% paraffins. There are often dozens of different oxygen compound compounds found in a paraffin feed and paraffin / olefin mixture prepared by the Fischer-Tropsch process and there is a need for a general process that works to remove all species of oxygen in order to use the paraffins. and paraffin / olefin mixture in a variety of processes. Thus, it is the combined presence of these compounds that is considered desirable to remove from paraffin feed and paraffin / olefin mixture. Moreover, in many applications of the present invention, it is desirable to be able to regenerate the adsorbents used to remove oxygenated compounds from the paraffin feed and paraffin / olefin mixture. There is considerable cost reduction in being able to reuse adsorbents after bed regeneration rather than frequent bed replacement.

SUMMARY OF THE INVENTION

The present invention comprises a process for removing oxygenated compounds from a stream comprising 50 to 99.99 wt% paraffins and 0 to 50 wt% olefins comprising passing a feed stream comprising one or more paraffin mixtures and C10 to C15 feed olefins and one or more oxygenated compounds through an adsorbent bed to remove essentially all oxygenated compound; and recovering paraffins and olefins, when present. The level of oxygenated compounds is below the level that is detectable with standard laboratory procedures such as gas chromatography. In some embodiments of the present invention, it is considered necessary to send the paraffin-rich stream through a second adsorbent bed comprising a molecular sieve to ensure complete removal of impurities from oxygenated compound. Typically, a 5A polishing bed is used to complete its removal from the paraffin-rich stream. This invention is particularly used in purifying feed streams for certain reactions. Trace amounts of oxygenated compounds can have detrimental effects upon an adsorbent / catalyst. Among the processes that are improved by the removal of oxygenated compounds according to the present invention are the dehydrogenation of paraffins to normal olefins and processes for separating normal paraffins from branched and cyclic hydrocarbons. In the case where the feed is a mixture of paraffins and olefins, this stream is suitable for direct alkylation with benzene after the oxygenated compound removal treatment prior to the formation of alkylated benzene. Accordingly, one embodiment of the present invention comprises a process for dehydrogenation of normal to olefin paraffins first comprising passing a paraffin stream comprising C10 to Q5 paraffins through at least one adsorbent bed comprising one or more adsorbents selected from the group consisting of silica gel. , activated alumina and alkaline or alkaline earth cation-exchange zeolite-X wherein the adsorbents essentially remove all oxygenated compounds from the paraffin stream by adsorption, and then pass the paraffin stream to a reactor containing a dehydrogenation catalyst to convert at least a portion of the paraffin stream to olefins. Another embodiment of the present invention comprises a process comprising first passing a C10 to C15 paraffin stream through at least one adsorbent bed comprising one or more adsorbents selected from the group consisting of silica gel, activated alumina and cation exchange zeolite alkaline or earth alkaline wherein the adsorbents essentially remove all oxygenated compounds from the paraffin stream by adsorption and then pass the paraffin stream into an adsorbent bed comprising a molecular sieve to separate n-paraffins from the paraffin stream.

Another embodiment of the present invention comprises a process comprising first passing the stream comprising 50 to 99.99 wt% C10 to C15 paraffins and 0 to 50 wt% olefins through at least one adsorbent bed comprising one or more selected adsorbents from the group consisting of silica gel, activated alumina and alkaline or alkaline earth cation-zeolite X-zeol in which the adsorbents essentially remove all oxygenated compounds from the paraffin stream by adsorption and then combining the stream with benzene and passing the stream. resulting alkylation in a reactor containing an alkylation catalyst to convert at least a portion of the olefins to the alkylated benzene.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 shows a breakdown of the adsorbent alumina feed of 1,000 ppm each of 2-undecanone, 2-undecanol, decyl alcohol, lauric acid and 2-dodecanol.

Figure 2 shows a feed split into a 1000 ppm adsorbent silica gel each of 2-undecanone, 2-undecanol, decylic alcohol, lauric acid and 2-dodecanol.

Figure 3 shows a feed split into a different adsorbent silica gel of 1,000 ppm each of 2-undecanone, 2-undecanol, decylic alcohol, lauric acid and 2-dodecanol.

Figure 4 shows a feed breakdown of a 1,000 ppm 13X adsorbent each of 2-undecanone, 2-undecanol, decyl alcohol, lauric acid and 2-dodecanol.

DETAILED DESCRIPTION OF THE INVENTION

The present invention comprises a process for the removal of oxygenated compounds from a paraffin and olefin mixture or a paraffin rich stream comprising passing the feed stream, comprising one or more C10 to C15 feed paraffins or mixture of paraffin and olefin and one or more oxygenated compounds through an adsorbent bed to remove essentially all oxygenated compound; and recovering the paraffins or paraffin and olefin mixture. Typically, the paraffin and olefin mixture referred to herein as olefin-typical streams will comprise up to 50% by weight of olefin with the remainder comprising paraffins, plus impurities. Up to 1% of the paraffin and olefin mixture or paraffin-rich streams will comprise impurities of oxygenated compound to be removed by the present invention. In paraffin-rich streams, streams typically comprise 99 wt% paraffins and sometimes up to 99.99 wt% paraffins. In a typical paraffin-rich or olefin-rich stream as such produced in a Fischer-Tropsch gas-to-liquid process it has been observed that numerous oxygenated hydrocarbon compounds are produced, including alcohols, aldehydes, ketones and acids. It is necessary to use a process to remove virtually all oxygenated compounds in order to employ these olefin rich paraffins or paraffins without adsorbent / catalyst poisoning that is used in processes such as paraffin conversion to olefins, alkylation of olefins with benzene and separation of n-paraffins from other paraffins. Table 1 illustrates the extensive list of oxygen compounds found in three olefin-rich paraffin or paraffin samples prior to treatment by the process of the present invention, all of which are removed by the process of the present invention. All numbers are in part per million.

Table 1

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Table 2 shows a summary of the types of oxygen compounds found in the diet.

Table 2

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In the practice of the present invention, a paraffin-rich or olefin-rich paraffin stream is first passed through an adsorbent bed containing at least one adsorbent selected from the group consisting of silica gel, activated alumina and alkaline cation exchange zeolite or alkaline earth. Zeolite X has a SiM12 ratio of 2.0 to 3.0. An X-zeolite with an Si / Al 2 ratio of 2, 2.3 or 2.5 is preferred.

In addition to the removal of oxygenated compounds, in some embodiments of the present invention it is necessary to remove compounds containing other group VIB elements from the periodic table of elements. In particular, when a well condensed lower grade gas is used which contains up to 0.7 wt% mercaptans, sulfites and disulfites, it is highly desirable to process this stream to reduce the sulfur compound level below pppm which is detrimental to Platinum catalyst used to prepare LAB. Sulfur compounds can be removed by the use of adsorbents known to one of skill in the art. Advantageous results can be found using an adsorbent bed comprising ADS-102, PED adsorbent available from UPO LLC, Des Plaines, Illinois.

The adsorbent bed may be exclusively dedicated to the treatment of paraffin-rich or olefin-rich paraffin streams or may be integrated with a chemical conversion process that uses the paraffin stream to effect further separations. The dedicated adsorbent bed is one where essentially its sole purpose is to remove oxygenated compounds from the paraffin stream regardless of whether only the paraffin stream passes through it or if the paraffin stream is combined with a chemical conversion process stream and the combined stream passes. across the bed. In an integrated adsorbent bed the paraffin stream and a process stream are combined and the adsorbent bed serves to remove at least one component in the process stream. For example, in processes for the alkylation process for preparing paraffin alkyl benzenes, paraffins are dehydrogenated and the dehydrogenation stream is typically passed through an adsorbent bed, such as zeolite 13X to remove undesirable aromatics. In such processes, the paraffin stream is preferably fed into the process after dehydrogenation and prior to adsorption of water and aromatics in the adsorption bed.

When dedicated, the adsorbent bed is typically operated at a temperature between 25 to 60 ° C and preferably is operated slightly above ambient (40 ° C). Although it has been observed that this adsorbent bed reduces the level of oxygenated compounds below the level that is measurable by gas chromatography, additional measurements are required since under some conditions these adsorbent beds become less efficient over time in removing the oxygenated compounds. to ensure that all oxygenated compound is removed. Thus, in preferred embodiments of the invention, it has been observed that a second adsorbent bed operating at elevated temperature between 150 ° C and 200 ° C containing a 5A adsorbent removes any residual oxygenated compounds not removed by the first bed. Adsorbent beds that are integrated with a process using the paraffin-rich or olefin-rich paraffin stream are generally operated under conditions suitable for the process.

After the adsorbent beds have reached their ability to remove oxygenated compounds from paraffin-rich streams, a regeneration procedure is followed to remove the adsorbed oxygenated compounds from the adsorbent bed. A gas or liquid is sent through the bed, which is kept at an elevated temperature for a period of time sufficient for the bed to be rejuvenated by removing oxygenated compounds. In one mode of the rejuvenation process, nitrogen was used as the regenerative gas at 3,000 GHSV5. The bed was first heated to 130 ° C for two hours and then the temperature increased to 250 ° C for a further three hours. Other regenerative gases or liquids may be used, such as available process streams. The bed may also be regenerated according to the procedure set forth in US 6,225,518 B1, incorporated herein by reference in its entirety. Normally, due to the low concentration of oxygenated compounds, the integrated adsorbent bed is regenerated or replaced based on its process performance.

EXAMPLE

Laboratory tests were performed to determine the extent of removal of oxygenated hydrocarbon compounds. The process is performed on a 20 mL stainless steel column. The column is installed in a closed box and is packaged with 20 mL of adsorbent. Initially, the closed box temperature is increased to the desired temperature, which was 40 ° C in this example. After stabilizing the temperature, the hydrogen peroxide containing hydrocarbon feed is introduced at a flow rate of 4 LHSV. The effluent is collected and analyzed for oxygenated compound impurities. The feed that was tested contained 1,000 ppm each of five typical kerosene-containing oxygen compounds: 2-undecanone, 2-undecanol, decylic alcohol, lauric acid and 2-dodecanol. Very clear breaks were noted with alumina, silica gel and adsorbent X-sodium types. In Figure 1, the alumina tested as an adsorbent was a spherical promoted alumina sold by UOP LLC, DES Plaines, Illinois as activated alumina 9139a. The adsorbent had a capacity of 21.95% by weight. In Figure 2, the adsorbent was Eagle 32-950 silica gel sold by Eagle Chemical Co., Inc., Mobile, Alabama. The adsorbent had a capacity of 19.76% by weight. In Figure 3, the adsorbent used was Grace 408 silica gel, sold by W.R. Grace, Grace Davison Division, Columbia, Maryland. The adsorbent had a capacity of 32.33% by weight. In Figure 4, MRG-E Molsiv adsorbent is used and is sold by UOP, DES Plaines, Illinois. The adsorbent had a capacity of 23.57% by weight. Each of the figures shows the substantial capacity of these adsorbents for oxygenated compounds, along with a clear breakdown after the adsorbent capacity has been reached. Also, lauric acid is strongly adsorbed by the adsorbent in all four cases.

Claims (9)

Process for removing oxygenated compounds from a stream comprising from 50 to 99.99% by weight of paraffins and 0 to 50% by weight of olefins, comprising: a) passing a feed stream, comprising 50 99.99 wt.% of one or more C10 to C15 feed paraffins, 0 to 50 wt.% olefins and one or more oxygenated compounds through an adsorbent bed to remove essentially all said oxygenated compounds; and b) recovering said paraffin (s) and olefins to form a purified stream of said adsorbent bed. Process according to claim 1, characterized in that said adsorbent bed comprises at least one adsorbent selected from the group consisting of alumina, silica gel and zeolite-X with alkaline or alkaline earth cation exchange. Process according to claim 2, characterized in that said adsorbent bed comprises NaX zeolite. Process according to Claim 1, 2 or 3, characterized in that said adsorbent bed is regenerated to remove said oxygenated compounds wherein said regeneration comprises heating said adsorbent bed to a sufficient temperature and for a period of time. sufficient time and pass a regenerative gas through said adsorbent bed to remove a desired portion of oxygenated compounds from said adsorbent. A process according to any one of claims 1-4, characterized in that it further comprises, after said paraffin and olefin stream passes through the adsorbent bed, passing said purified stream to a second adsorbent bed comprising adsorbent 5A. to further remove said oxygenated compounds from said purified stream. Process according to any one of claims 1-5, characterized in that said paraffin and olefin stream is a feed stream for a chemical conversion process using an adsorbent bed and the adsorbent bed to remove said streamers. Oxygenated compounds comprise the adsorbent bed in the process. Process according to Claim 6, characterized in that the chemical conversion process is for benzene alkylation comprising paraffin dehydrogenation, removal of aromatics in an adsorption bed and reaction of benzene dehydrogenated paraffin, and the bed. Adsorbent for the removal of oxygenated compounds comprises an adsorbent bed for the removal of aromatics. Process according to Claim 6 or 7, characterized in that said paraffin and olefin stream is fed in the chemical conversion process subsequent to dehydrogenation and prior to the removal of the aromatics in the adsorbent bed. A process according to claim 7, characterized in that it further comprises passing said paraffin stream into an adsorbent bed comprising a molecular sieve for separating n-paraffins from said paraffin stream.