CA2212892A1 - Pretreatment of catalyst support to enhance catalytic dehydrogenation of a hydroquinone - Google Patents
Pretreatment of catalyst support to enhance catalytic dehydrogenation of a hydroquinoneInfo
- Publication number
- CA2212892A1 CA2212892A1 CA002212892A CA2212892A CA2212892A1 CA 2212892 A1 CA2212892 A1 CA 2212892A1 CA 002212892 A CA002212892 A CA 002212892A CA 2212892 A CA2212892 A CA 2212892A CA 2212892 A1 CA2212892 A1 CA 2212892A1
- Authority
- CA
- Canada
- Prior art keywords
- catalyst
- catalyst support
- earth metal
- support
- rare earth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C46/00—Preparation of quinones
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/63—Platinum group metals with rare earths or actinides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0201—Impregnation
- B01J37/0205—Impregnation in several steps
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/02—Preparation of sulfur; Purification
- C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
- C01B17/0495—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by dissociation of hydrogen sulfide into the elements
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/04—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of inorganic compounds, e.g. ammonia
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Combustion & Propulsion (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Catalysts (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
A process is provided for preparing a catalyst system containing a catalyst support and an associated catalyst used to catalytically dehydrogenate a hydroquinone. In accordance with the process, the catalyst support is pretreated by selecting a porous alumina of silica catalyst support and contacting it with an aqueous solution of an alkali metal salt, alkaline earth metal salt, or rare earth metal salt to produce the corresponding metal oxide on the surface of the support in a quantity sufficient to reduce the acidity thereof. The metal oxide-treated support is then contacted with a metal catalyst to produce a catalyst system having enhanced utility in the selective conversion of a hydroquinone to its corresponding quinone and hydrogen gas.
Description
W O96/33015 PCT~US96/02532 PRETREATIJENT OF A CATALYST SUPPORT TO ENHANCE
CATALYTIC DEHYDROGENATION OF A HYDROQUINONE
This is a continuation-in-part application of application Serial No.
08/315,174 filed on September 29, 1994, which is a continuation-in-part application of application Serial No. 08/172,007 filed on December 22, 1993.
R~r~Kt~Rt~l lNn ~F THF INVFNTI-~N
Technical Field:
The present invention relates to a p.ocass for pr~pa,ing a catalyst system used to dehy h~efiale a hydroquinone, and more partlcularly, to such a ~rucess v.:,er~in the support of the catalyst system is pr~trdated to enhance the conversion of the hydroquinone to its cl;-lds4orldi.~ quinone and hydrogen.
Background Infol",dtion:
Catalytic del-yJ~ogd.,alion of a hydroquinone to its cGI~esponding quinone and hydrogen is generally known. For exampls, the following puh' c~tions inco"~,dted herein by reference; Plummer, ~Sulfur and I Iyd~en from H2S~, H~J~ocaiL,on r~ocessin~, April 1987; U.S. Patent 4,592,905 to Plummer ~t a~ and U.S. Patent 5,334,363 to Plummer, all teach pn~cesses for recovering solid sulhr and hyd~en gas frDm a gas stream co,lta;ning hydrogen sulfide, wherein the step of catalytically del-JJ~ugu~ndling an anthrahydroquinone to its corresponding anthraquinone and hydrogen is integral to each process.
In ac~r~nce with the abovo ~efe~nc~J prior art processes hydrogen sulfide contained in a gas strearn, such as a l"~d,~rbon refinery off-gas, is dissolved in a solvent also having an a,ltl.r~uinone d;ssolvod therein. The hydrogen sulfide and a,ltl-raquinone are ,e~,leJ in sDlution to obtain solid sulfur and the cG..~sponding al~thrdhydroquinone of the a.nl,.~uinone. The 30 solid sulfur product is recovered from the rea,tiol- so~ution and the a, Itl ,ra~uinone is .~enerdte.l for recycle to the hydrogen sulfide reaction step by catalytically dehydrogenating the al ~tl,rdl)~droquinone. Hydrogen gas also results as a product of the anthraquinone regefi~r~tion step.
W O96/33015 PCT~US96/02532 The p.ucess taught by Plummer in ~h~L~I) r~ss,i-g invesli~es a number of ~Jiffer6nl suppGIl~ metal catalyst systems for use in the regeneration step to de~r",ine the effect of the different systems on the conversion of anthrahydroquinone to its corresponding anthraquinone. It is 5 believed that the selectivity of the conversion step is allùl)~ly dependent on the catalyst system parameters, which, if in"~rop~tly ~~l~cted. can undesirably result in re~uced yields of the co"espol,ding a.)~l..~uinone and concurrently increased yields of less desirable con"~ounds, such as the c~"dsponding anthrone and anthranol.
The Plummer process found that the s~ecific type of metal catalyst selected is an i""~Gilant parameter for the catalvtic conversion of the ar,ll,rdl"~droquinone to anthraquinone. The Plummer prucess also found that the catalytic dehyd~uyenation step is strongiy dependent on the characte,islics of the matefial selected as a support for the metal catalyst. In particular, the15 Plummer p,ucess found that selective dehydrogenation of the ar,ll ,rdhydroquinone back to a, ~l "~uinone is favored by the use of only slightly acidic catalyst supports such as silica or alumina, or by the use of basic supports such as ",synesium oxide. More addic catalyst supports such as silica-alumina ur,desi,dbly yield relatively low conversions of 20 a,ltl,rdhydroquinone to anthraquinone and yield relatively high conversions of anthrahydroquinone to anll,ru,)e.
The present invention re~yni es a need for an improved catalytic dehydrogenation ~.lucess that converts a hydroquinone to hydrogen gas and its co"e,spording quinone. Aocordingly, it is an object of the pnasenl invention25 to provide a catalytic dehyJ~uger,ation pr~cess havin~ enl~anced selectivityfor the conversion of a hydroquinone to its co.,~spo.,ding quinone. More particularly, it is an obiect of the p.es6nt invention to provide a catalyst system including a catalyst support, having onl)anc6J selectivity for the catalytic conversion of a hydroquinone to its cGIlespGncling quinone. It is further an 30 object of the present invention to provide a p,ucess for pl~,e~ting a catalyst support that enl~ances the selectivity thereof when employed in a process for catalytically convértin~ a hydroquinone to its cG"~spo.,ding quinone. It is yet W O96/33015 PCTrUS96/02532 another object of the prese"l invention to provide a pru~ess for recovering sulfur and g~seolJs hydro~en from a hydro~en sulfide containing gas stream employing a quinone, wherein a dehyd~nalio,) catalyst effectively regene.~les the quinone from its correspor,din~ hydroquinone. These objects 5 and others are achieved in ac~rdance with the invention .Jeselibed her~ner.
~1 IMMARY nF THF INVF~TlnN
In accG,~a,)ce with one e"t,GJ;",ent, the pr~e.ll invention is a plucess for preparing a catalyst system containing a c~aly~t support and an ~coc: ~ed 10 catalyst used to catalytically deh~dl ~ ~ndt~a a hydroquinone, selectively converting the hydroquinone to its cGr,espond;n~ quinone and hydr~en gas.
In accordance with anotl,er ei,d~i"~nl, the prdsent invention is a pf~cess for pr~l,eatinç~ the ~talyst support used in conjunction with the ~ te-l catalyst to dehy Jt~endte the hydr~quinone. In ac~,Jano~ with a further elllL~i,llel)l, 1~ the present invention is the catalyst system prepared in accG'dance with the process d;sclQsed herein. In ac~,~nce with a more particular e"~b~i."enl, the present invention is a prucess employing a quinone to f~vGr sulfur and g~ceo~s h~J~ugen from a h~d~ugen sulfide con~niny gas stream, wl,erein the catalyst system of the p,~ser~ invention is used to regenerate the quinone from 20 its corresponding hydroquinone.
The pr~senl prucess of pr~l,e~ting a ~t~ l support cG~".Iises selecting a porous catalyst support from among sized alumina or silica and calcining the selected support. The calcined support is cont~t~J with an ~queous solution conlaining a salt selQcte~ from the group consisli,)~ of alkali25 metal salts, alkaline earth metal salts, rare earth metal salts, and mixturesthereof, thereby l,eating the surface of the support with the ~ 1~J salt. The salt-treated support is then dried and cal~n2~1 converting the salt to a corresponding metal oxide. The desired pretn~ateJ catalyst support is produced ll,ereby, having a sufficient quantity of metal oxide placed on the 30 catalyst support to reduce the acidity of the support.
The pr~s6,~ prucess of pr~ a catalyst system co""~,is~s s~le 1ing a metal catalyst from the group consisting of nickel, cobalt. the platinum group W O96/33015 4 PCTrUS96/02532 metals and mixtures thereof. A pretreated catalyst support prepared in the above-descliL~ ,l~nerisconla,1ecl with an ~qlJec~s so!ution conl~ning the selected metal catalyst preferably in a metal salt form. The metal catalyst solution augments the metal oxide on the pret,dal~l catalyst support with the 5 selected metal catalyst. The metal catalyst-l.aal~ caldly~l support is then dried and calcined producing the d6Sil'13CI eatulyal system thereby, comprising the catalyst placed on the pr~t,e~ted catalyst support. The catalyst system of the present invention has enhnnced utility in the selective conversion of a hydroquinone to its corrssponding quinone and hydro~en gas. The invention 10 will be further understood both as to its use and cG~ Gs;tion, from the accompanying descriplion.
RRIFF nF~r~RlpTlt~N ~~F THF nRAwlN~
The figure is a plot of te."~,er~lJre pr~._.,.."~ c~dsG-~tion (TPD) 15 profiles for a catalyst support treat6d in acc~nJance with the process of the present invention and for a co",~rable urlt,dal~ cat~ly;,l support.
nF.~:CRlPTI~ N t-)F l'lt~ HI~ ) FME~ODIMENTS
The present invention relates to the catalytic dehydrogGndtion of a 20 hydroquinone to its cGIld~rK~in~ quinone and h1J~u~en (H2). Hydroquinones having utility herein include anll,rah~droquinones, Len ohydroquinones naphthahydroquinones, and mixtures tl,er~r. CGIl~spGndin~ quinones having utility herein include a,ltl,raq.linones, ben~uinones, naphll,~.Jinones, and mixtures thereof, respecti./ely. The dehydrogGndtio~ z_tion is typically one 25 stage of a multi-stage industrial pn~cess, wherein the quinone is ,~enerdled from the hydroquinone for use in another stage of the pr~cess and hydrogen is recovered as a product gas.
For example, the dehydrogenation ,~tiGn is employed to regenerata a quinone from a hydroquinone as a stage of an industrial pr~ss to recover 30 sulfur from hydrogen sulfide ~H2S). In the sulfur recove.lr prucess, a selected quinone is Jissolved in a s9'~ted polar oryan c sotvent. Suitable polar organic solvents include N-methyl-2-pyrrolidinone, N,N~L"atl-~rlaceta"lide, N,N-W O96/33015 PCTrUS96/02532 dimethylfomlamaide, sulfolane (tetrahyJ~-~tll:sphene~ 3ioxi-J~), aeetonitrile, 2-nitropropane, propylene Ch bonale and mixtures ll ,er~of. The most pr~fe, .
solvent is N-methyl-2-pyrrolidinone (NMP). Suitable quir,ones are those having relatively high solubilities in the above li~led polar or~anic solvents, and 5 include sueh antl"~uinones as ethyl a,ltl.r~uinone, t-butyl anthr~inone, t-amyl anthraquinone, s-amyl anthraquinone or mixtures ll,er~of.
The quinone-conlaining solvent is fed to an H2S conversion reactor along with a feed gas stream wnta nir~ a h~ aon sulfide gas. If the feed gas stream a~ilionally col-t;ans large quanLL ~s of other ~ases that are inert to the 10 process, such as nitrogen, carbon dioxide, ,etl.ana or other low molQ~Ji~r weight hydrocarbon gases, the feed gas stream is initially conla~,1ecJ with the quinone-containing solvent in an a~sG,L,er ahead of the H2S conversion reactor.
In any case, the solvent preferentialiy solubili~es the h~d~u~en sulfide in the feed gas stream upon conlact fomming a re~,tiGn sDlu~ion that is ",ainlained in the reactor at a te---pe-~ure from about 0~C to about 70~C, an H2S partial pressure from about 0.05 to about 4.0 dt---ospheres, and for a time sufficient to convert the hydrogen sulfide and quinone in the r~.;tion solution to insoluble sulfur and the co-,esponJing hydroquinone.
Upon conversion of the .~ t~, the re~1ion solution is removed from the H2S conversion reactor and the insoluble sulfur product, in the form of S
or other sulfur polymers, is separated from the r~a~tion so'~ion by filtration, centrifugation or any other means known in the art. The l~--,aincJer of the ,ea~tion solution, which contains the polar organic solvGnt, hydroquinone, any ur,rt:~tecl quinone, and any L"~reacteJ constituents of the feed gas stream, is heated to a temperature from about 100~C to about 150~C at al.-,Gsphe,ic pressure and fed to a flash tank. Any unre~l~ teed gas constituents, such as hy.J~ugen sulfide and car~on dioxide, are r~e.r~ from the rba~,1iGn sol~nion in the flash tank and recycled to the H2S conversion rb~.,tor. The remaining solution is v:;lh.l~ .l from the flash tank and pr~fer~ly heated further to a te" ,~r~lure from about 1 50~C to about 350~C at a pressure at least sufficient to prevent solvent boiling. The heated s~!l tion is then fed to a dehydrogenation reactor where the hydroquinone is catalytically converted to W O96/33015 6 PCTnUS96/02532 quinone and hydrogen gas under the above-stated temperature and pressure conditions.
In ac~iJance with the present invention, it has been discovered that a catalyst system including a metal catalyst and a catalyst support, wherein the 5 catalyst system is prepared in a speoific ..,anner, une~tpecte~ly results in improved h~nltu~en and quinone selectivity when a hydroquinone is catalytically dehyd~enal~. In particular, it has been discovered that pr~t.eal."ent of the catalyst support in a sp~ific "~nn~rto reduce the acidity ~I,or~of unexpectedly results in improved l"~J~en and quinone selecffvity. Co,lt,s~ncJi, !aly, the 10 present invention results in .lecreasecl produ~tion of undesirable by-prod~cts, such as anthrones and/or ar,ll,rdnols, during the dehyJ~enalion rea~.tiGn.
Pretleatl~lent of the catalyst support cG"".,ises ssl~ting a porous catalyst support from among either alumina (Al2O,) or silica (SiQ ). The catalyst support has a surface area of at least about 100 m2/~ and pr~fer~ly 15 at least about 200 m2/g. The catalyst support can be cn~shed and sieved to a desil~ average particle size gid~terthan about 0.3 mm, and pr~,fe.~ greater than about 0.5 mm. The sized catalyst support is calci.-eJ for several hours or more at a temperature of at least about 1 20~C, and ~,r~fer~ly at least about 500~C. The calcined support is then contactecl with an ~lneous solution of a 20 salt s~ te~ from the group con~sli,~ of alkali metal salts, alkaline earth metal salts, rare earth metal salts, and mixtures thereof. A pl~.fe..~J salt is a rareearth metal salt, such as a salt of lanlhanum, and in particular lantl.anum nitrate.
Contacting ot the catalyst support with the salt solution can be ac~-"plished by ~,~te,ir~ a solution of the s219cte~ salt onto the support whilemixing and shaking the support to obtain good contacting bet~raon the support surface and the selected salt. Conla,tin~ of the cataiyst support with the salt solution can altematively be accGi"plished by other means ~pardnl to the r skilled artisan. In any case, conla,ting between the catalyst support and the selected salt places the selected salt on the surface of the catalyst support.
Treal."ent of the catalyst support is completed by ~~."o~ing the salt-treated support from the ~ueovs salt solution and drying the support with an W O96/33015 PCTrUS96/02532 air flow heated to a te"~per~ re of at least about 120~C. The dried catalyst support is then caicined, pr~6,al~!y under s~bP~ntialiy the same cor,.JiliGns asdescribed above, thereby converting the 5elected sait on the surface of the catalyst support to a cGr,~sponding basic alicali metal oxide, alicaline earth 5 metal oxide, rare earth metal oxide, or mixture tl,oreof, ~specti./eiy. A
prefellt~d basic metal oxide is a rare earth metal oxide, such as an oxide of lanthanum.
A suffident quantity of the basic metal oxide is placed on the support to reduce the acidity ll ,e~of. The amount of metal oxide placed on the cataiyst support is generally within a range between about 1.0 weight % and aioout 10.0 weight %, and p,~felabiy within a rar~e between about 2.0 wei~ht % and about 5.0 weight %.
i~reparation of the cataiyst system is imple.,.anle~l with s~l3~tion of a metal catalyst from the group consislin~ of nickel, cobalt, the platinum ~roup 15 metals, and mixtures tl,ereof. The platinum group metals as cJefine~ herein consist of platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), osmium (Os) and iridiurr (Ir). Of the metal caWysts ~ os~J herein the platinum ~roup metals are piefe,-ed, and platinum is most pr~f~..~. The 5~ led metal catalyst is placed on the prel~eale.l catalyst support by contacting the 20 pretreated catatyst support with a solution of the sGlected metal catalyst, pr~fe(al~ly in the form ot one of its salts, such as a solution of platinum chloride.
Contacting of the catalyst support with the seleute~ metal catalyst sol ~tion can be acoon,,l shed in su~ tially the same ,..anner as desc,;~ed above or, alternatively, by other means appar~nt to the skilled artisan. In any 25 case, conla~ting between the catalyst support and the sele.AeJ metal catalyst solution places the metal catalyst on the surface of the ç~ l support augmenting the metal oxide treatment. A sufficient quantity of the metal catalyst is placed on the support to enable orr~ti~o pe,h,r--.e..)ce of the resulting catalyst system in the conversion of hydroquinone to its co. .~ponding30 quinone. The amount of metal catalyst placed on the ~r~lr~ated catalyst support is generally within a range bet-.3E., about 0.01 weight % and about 3.0 weight %, and pr~ferdbly within a range between about 0.1 wei~ht % and about W O96/33015 PCTrUS96/02532 2.0 weight %. The resulting catalyst system is then dried and calcined in s~ st~ntially the same manner as desciibe J above.
The catalyst system preF~.~ in the "~nner of the pr~senl invention has specific utility in the above~lescrlbecl dehy~ Gnalion r~a~tion of the sulfur recovery process, wherein the catalyst converts a hydroquinone dissolved in the polar solvent to hydlogan gas that is recovered as a co,n",er~al product and to the corr6s~0n.iing quinone that is recycled to the H2S conversion reactor.
The following examples delllonalldle the p~ arK~ utility of the present invention, but are not to be constnued as limitin~ the scope tl,erdof.
A series of test runs are pelh,r",ed in a dehydro~enation reactor to c~ele""ine the selechvity that ditf~,e,lt c~atyst systerns exhibit in the conversion of an anthrahydroquinone to its cor,aspoi-~in~ arni-,~ inone and hy.J~u~on.
The reactor feed co--~osiliGn for all runs is pr~areJ co,..~,n~inç~ a mixture oft-butyl anthrahydroquinone (H2T8AQ) and t-butyl a,nilra~ inone (TBAQ) in a N-rnethyl-2-pyrrolidinone (NMP) solvent. The relative quantity of total quinone species (H2TBAQ and TBAQ) in the feed is 25 % by weight. The mole ratio of H2TBAQ to T8AQ in the feed is 76.0:24Ø
In each test run, the catalytic dehyd~enalion r~t~r is charged with a different catalyst system comprising a catalyst and a catalyst support. The reactor is a packed stainlsss steel tube having a diameter of 1.27 cm. The different catalyst systems are characterized below:
Catalyst Catalyst Wt % on Support Oxide Wt%C~
.System Typa .~, ~rt Ty~a ~ nn , A Pt 2.75 SjO2 La2O3 2.50 B Pt 2.75 SiO2 C Cr2O3 12 Al2O3 The silica (SiO2) type catalyst support is D~vidson ~7 having a pore volume of 1.0 cm3 and contains 99.5 % SiO2 by weiç~ht. The alumina (A~O3) type catalyst support is Norton having a pore volume of 0.57 to 0.67 cm3 and contains 99.85 % Al2O3 by weight. Each of the catalyst supports has a surface area of 260 m2/g.
Catalyst system A is a catalyst system of the pr~sent invenlion having a prel. ealed catalyst support p~pareJ in ac~ance with the manner described herein. The support is initially crushed and sieved to an av~r~e particle size of 0.56 mm. The sized support is calcinecl ovemight at a tamperature of 500~C. Lantl,an.lm oxide (La2O3) is placed on the calcined support by d~.~pN;5~ adding an ~ eous solutien of la.lt~ m nitrate (La2(NO3)3) to the support while continuously mixin~ and shaking the support, thereby producing a la"ll-~)~Jm nitrate on the support surface. The tlt~al6d support is then dried with air flow for 2 hours at 120~C and calcined ovemight at 500~C to obtain the desired lanthanum oxide~ te~ support. A platinum (Pt) catalyst is then placed on the pr~t,edled support by ~l~o,~/;3a adding an ~clueous solution of platinum chlGiilJe (PtCI~) to the pret,~dted support while continuously mixing and shaking the support. The catalyst system is dried with air flow for 2 hours at 120~C, calcined ovemi~ht at 500~C, cooled to room temperature, and stored in a ~lesi~tsr for use.
Catalyst systems B and C are prior art oalaly--l systems prepared in sub~lPnlially the same manner as cJes~-ib6~1 above, but without pret.eat",ent W O9613301S PCTrUS96/02532 of the catalyst support. The alumina eatalyst support is crushed and sieved to a particle size from 14 to 20 mesh.
The amount of catalyst system ~ ,ary~ to the packed bed of the reactor in each nun is 7.8 em~. The reaetor is ",aintained at a te""~cr~.lre betwGGn 265~C and 275~C and at a hyJ~en pressure bet-v600 430 kPa and 500 kPa.
In eaeh run the feed is retained in the dehyd~u~enatiGn reaetor for a residence time of 1 minute. The product is then removed from the reactor and analyzed to .Jet6""i,-e the degree of total H2TBAQ conversion and conversion of H2TBAQ
to TBAQ and hydro~en. The results are set forth in the table below.
TABLE OF RESULTS
Run Catalyst H2TBAQ Conv~,sion (mole%) ystem IQ~al To TR~
CATALYTIC DEHYDROGENATION OF A HYDROQUINONE
This is a continuation-in-part application of application Serial No.
08/315,174 filed on September 29, 1994, which is a continuation-in-part application of application Serial No. 08/172,007 filed on December 22, 1993.
R~r~Kt~Rt~l lNn ~F THF INVFNTI-~N
Technical Field:
The present invention relates to a p.ocass for pr~pa,ing a catalyst system used to dehy h~efiale a hydroquinone, and more partlcularly, to such a ~rucess v.:,er~in the support of the catalyst system is pr~trdated to enhance the conversion of the hydroquinone to its cl;-lds4orldi.~ quinone and hydrogen.
Background Infol",dtion:
Catalytic del-yJ~ogd.,alion of a hydroquinone to its cGI~esponding quinone and hydrogen is generally known. For exampls, the following puh' c~tions inco"~,dted herein by reference; Plummer, ~Sulfur and I Iyd~en from H2S~, H~J~ocaiL,on r~ocessin~, April 1987; U.S. Patent 4,592,905 to Plummer ~t a~ and U.S. Patent 5,334,363 to Plummer, all teach pn~cesses for recovering solid sulhr and hyd~en gas frDm a gas stream co,lta;ning hydrogen sulfide, wherein the step of catalytically del-JJ~ugu~ndling an anthrahydroquinone to its corresponding anthraquinone and hydrogen is integral to each process.
In ac~r~nce with the abovo ~efe~nc~J prior art processes hydrogen sulfide contained in a gas strearn, such as a l"~d,~rbon refinery off-gas, is dissolved in a solvent also having an a,ltl.r~uinone d;ssolvod therein. The hydrogen sulfide and a,ltl-raquinone are ,e~,leJ in sDlution to obtain solid sulfur and the cG..~sponding al~thrdhydroquinone of the a.nl,.~uinone. The 30 solid sulfur product is recovered from the rea,tiol- so~ution and the a, Itl ,ra~uinone is .~enerdte.l for recycle to the hydrogen sulfide reaction step by catalytically dehydrogenating the al ~tl,rdl)~droquinone. Hydrogen gas also results as a product of the anthraquinone regefi~r~tion step.
W O96/33015 PCT~US96/02532 The p.ucess taught by Plummer in ~h~L~I) r~ss,i-g invesli~es a number of ~Jiffer6nl suppGIl~ metal catalyst systems for use in the regeneration step to de~r",ine the effect of the different systems on the conversion of anthrahydroquinone to its corresponding anthraquinone. It is 5 believed that the selectivity of the conversion step is allùl)~ly dependent on the catalyst system parameters, which, if in"~rop~tly ~~l~cted. can undesirably result in re~uced yields of the co"espol,ding a.)~l..~uinone and concurrently increased yields of less desirable con"~ounds, such as the c~"dsponding anthrone and anthranol.
The Plummer process found that the s~ecific type of metal catalyst selected is an i""~Gilant parameter for the catalvtic conversion of the ar,ll,rdl"~droquinone to anthraquinone. The Plummer prucess also found that the catalytic dehyd~uyenation step is strongiy dependent on the characte,islics of the matefial selected as a support for the metal catalyst. In particular, the15 Plummer p,ucess found that selective dehydrogenation of the ar,ll ,rdhydroquinone back to a, ~l "~uinone is favored by the use of only slightly acidic catalyst supports such as silica or alumina, or by the use of basic supports such as ",synesium oxide. More addic catalyst supports such as silica-alumina ur,desi,dbly yield relatively low conversions of 20 a,ltl,rdhydroquinone to anthraquinone and yield relatively high conversions of anthrahydroquinone to anll,ru,)e.
The present invention re~yni es a need for an improved catalytic dehydrogenation ~.lucess that converts a hydroquinone to hydrogen gas and its co"e,spording quinone. Aocordingly, it is an object of the pnasenl invention25 to provide a catalytic dehyJ~uger,ation pr~cess havin~ enl~anced selectivityfor the conversion of a hydroquinone to its co.,~spo.,ding quinone. More particularly, it is an obiect of the p.es6nt invention to provide a catalyst system including a catalyst support, having onl)anc6J selectivity for the catalytic conversion of a hydroquinone to its cGIlespGncling quinone. It is further an 30 object of the present invention to provide a p,ucess for pl~,e~ting a catalyst support that enl~ances the selectivity thereof when employed in a process for catalytically convértin~ a hydroquinone to its cG"~spo.,ding quinone. It is yet W O96/33015 PCTrUS96/02532 another object of the prese"l invention to provide a pru~ess for recovering sulfur and g~seolJs hydro~en from a hydro~en sulfide containing gas stream employing a quinone, wherein a dehyd~nalio,) catalyst effectively regene.~les the quinone from its correspor,din~ hydroquinone. These objects 5 and others are achieved in ac~rdance with the invention .Jeselibed her~ner.
~1 IMMARY nF THF INVF~TlnN
In accG,~a,)ce with one e"t,GJ;",ent, the pr~e.ll invention is a plucess for preparing a catalyst system containing a c~aly~t support and an ~coc: ~ed 10 catalyst used to catalytically deh~dl ~ ~ndt~a a hydroquinone, selectively converting the hydroquinone to its cGr,espond;n~ quinone and hydr~en gas.
In accordance with anotl,er ei,d~i"~nl, the prdsent invention is a pf~cess for pr~l,eatinç~ the ~talyst support used in conjunction with the ~ te-l catalyst to dehy Jt~endte the hydr~quinone. In ac~,Jano~ with a further elllL~i,llel)l, 1~ the present invention is the catalyst system prepared in accG'dance with the process d;sclQsed herein. In ac~,~nce with a more particular e"~b~i."enl, the present invention is a prucess employing a quinone to f~vGr sulfur and g~ceo~s h~J~ugen from a h~d~ugen sulfide con~niny gas stream, wl,erein the catalyst system of the p,~ser~ invention is used to regenerate the quinone from 20 its corresponding hydroquinone.
The pr~senl prucess of pr~l,e~ting a ~t~ l support cG~".Iises selecting a porous catalyst support from among sized alumina or silica and calcining the selected support. The calcined support is cont~t~J with an ~queous solution conlaining a salt selQcte~ from the group consisli,)~ of alkali25 metal salts, alkaline earth metal salts, rare earth metal salts, and mixturesthereof, thereby l,eating the surface of the support with the ~ 1~J salt. The salt-treated support is then dried and cal~n2~1 converting the salt to a corresponding metal oxide. The desired pretn~ateJ catalyst support is produced ll,ereby, having a sufficient quantity of metal oxide placed on the 30 catalyst support to reduce the acidity of the support.
The pr~s6,~ prucess of pr~ a catalyst system co""~,is~s s~le 1ing a metal catalyst from the group consisting of nickel, cobalt. the platinum group W O96/33015 4 PCTrUS96/02532 metals and mixtures thereof. A pretreated catalyst support prepared in the above-descliL~ ,l~nerisconla,1ecl with an ~qlJec~s so!ution conl~ning the selected metal catalyst preferably in a metal salt form. The metal catalyst solution augments the metal oxide on the pret,dal~l catalyst support with the 5 selected metal catalyst. The metal catalyst-l.aal~ caldly~l support is then dried and calcined producing the d6Sil'13CI eatulyal system thereby, comprising the catalyst placed on the pr~t,e~ted catalyst support. The catalyst system of the present invention has enhnnced utility in the selective conversion of a hydroquinone to its corrssponding quinone and hydro~en gas. The invention 10 will be further understood both as to its use and cG~ Gs;tion, from the accompanying descriplion.
RRIFF nF~r~RlpTlt~N ~~F THF nRAwlN~
The figure is a plot of te."~,er~lJre pr~._.,.."~ c~dsG-~tion (TPD) 15 profiles for a catalyst support treat6d in acc~nJance with the process of the present invention and for a co",~rable urlt,dal~ cat~ly;,l support.
nF.~:CRlPTI~ N t-)F l'lt~ HI~ ) FME~ODIMENTS
The present invention relates to the catalytic dehydrogGndtion of a 20 hydroquinone to its cGIld~rK~in~ quinone and h1J~u~en (H2). Hydroquinones having utility herein include anll,rah~droquinones, Len ohydroquinones naphthahydroquinones, and mixtures tl,er~r. CGIl~spGndin~ quinones having utility herein include a,ltl,raq.linones, ben~uinones, naphll,~.Jinones, and mixtures thereof, respecti./ely. The dehydrogGndtio~ z_tion is typically one 25 stage of a multi-stage industrial pn~cess, wherein the quinone is ,~enerdled from the hydroquinone for use in another stage of the pr~cess and hydrogen is recovered as a product gas.
For example, the dehydrogenation ,~tiGn is employed to regenerata a quinone from a hydroquinone as a stage of an industrial pr~ss to recover 30 sulfur from hydrogen sulfide ~H2S). In the sulfur recove.lr prucess, a selected quinone is Jissolved in a s9'~ted polar oryan c sotvent. Suitable polar organic solvents include N-methyl-2-pyrrolidinone, N,N~L"atl-~rlaceta"lide, N,N-W O96/33015 PCTrUS96/02532 dimethylfomlamaide, sulfolane (tetrahyJ~-~tll:sphene~ 3ioxi-J~), aeetonitrile, 2-nitropropane, propylene Ch bonale and mixtures ll ,er~of. The most pr~fe, .
solvent is N-methyl-2-pyrrolidinone (NMP). Suitable quir,ones are those having relatively high solubilities in the above li~led polar or~anic solvents, and 5 include sueh antl"~uinones as ethyl a,ltl.r~uinone, t-butyl anthr~inone, t-amyl anthraquinone, s-amyl anthraquinone or mixtures ll,er~of.
The quinone-conlaining solvent is fed to an H2S conversion reactor along with a feed gas stream wnta nir~ a h~ aon sulfide gas. If the feed gas stream a~ilionally col-t;ans large quanLL ~s of other ~ases that are inert to the 10 process, such as nitrogen, carbon dioxide, ,etl.ana or other low molQ~Ji~r weight hydrocarbon gases, the feed gas stream is initially conla~,1ecJ with the quinone-containing solvent in an a~sG,L,er ahead of the H2S conversion reactor.
In any case, the solvent preferentialiy solubili~es the h~d~u~en sulfide in the feed gas stream upon conlact fomming a re~,tiGn sDlu~ion that is ",ainlained in the reactor at a te---pe-~ure from about 0~C to about 70~C, an H2S partial pressure from about 0.05 to about 4.0 dt---ospheres, and for a time sufficient to convert the hydrogen sulfide and quinone in the r~.;tion solution to insoluble sulfur and the co-,esponJing hydroquinone.
Upon conversion of the .~ t~, the re~1ion solution is removed from the H2S conversion reactor and the insoluble sulfur product, in the form of S
or other sulfur polymers, is separated from the r~a~tion so'~ion by filtration, centrifugation or any other means known in the art. The l~--,aincJer of the ,ea~tion solution, which contains the polar organic solvGnt, hydroquinone, any ur,rt:~tecl quinone, and any L"~reacteJ constituents of the feed gas stream, is heated to a temperature from about 100~C to about 150~C at al.-,Gsphe,ic pressure and fed to a flash tank. Any unre~l~ teed gas constituents, such as hy.J~ugen sulfide and car~on dioxide, are r~e.r~ from the rba~,1iGn sol~nion in the flash tank and recycled to the H2S conversion rb~.,tor. The remaining solution is v:;lh.l~ .l from the flash tank and pr~fer~ly heated further to a te" ,~r~lure from about 1 50~C to about 350~C at a pressure at least sufficient to prevent solvent boiling. The heated s~!l tion is then fed to a dehydrogenation reactor where the hydroquinone is catalytically converted to W O96/33015 6 PCTnUS96/02532 quinone and hydrogen gas under the above-stated temperature and pressure conditions.
In ac~iJance with the present invention, it has been discovered that a catalyst system including a metal catalyst and a catalyst support, wherein the 5 catalyst system is prepared in a speoific ..,anner, une~tpecte~ly results in improved h~nltu~en and quinone selectivity when a hydroquinone is catalytically dehyd~enal~. In particular, it has been discovered that pr~t.eal."ent of the catalyst support in a sp~ific "~nn~rto reduce the acidity ~I,or~of unexpectedly results in improved l"~J~en and quinone selecffvity. Co,lt,s~ncJi, !aly, the 10 present invention results in .lecreasecl produ~tion of undesirable by-prod~cts, such as anthrones and/or ar,ll,rdnols, during the dehyJ~enalion rea~.tiGn.
Pretleatl~lent of the catalyst support cG"".,ises ssl~ting a porous catalyst support from among either alumina (Al2O,) or silica (SiQ ). The catalyst support has a surface area of at least about 100 m2/~ and pr~fer~ly 15 at least about 200 m2/g. The catalyst support can be cn~shed and sieved to a desil~ average particle size gid~terthan about 0.3 mm, and pr~,fe.~ greater than about 0.5 mm. The sized catalyst support is calci.-eJ for several hours or more at a temperature of at least about 1 20~C, and ~,r~fer~ly at least about 500~C. The calcined support is then contactecl with an ~lneous solution of a 20 salt s~ te~ from the group con~sli,~ of alkali metal salts, alkaline earth metal salts, rare earth metal salts, and mixtures thereof. A pl~.fe..~J salt is a rareearth metal salt, such as a salt of lanlhanum, and in particular lantl.anum nitrate.
Contacting ot the catalyst support with the salt solution can be ac~-"plished by ~,~te,ir~ a solution of the s219cte~ salt onto the support whilemixing and shaking the support to obtain good contacting bet~raon the support surface and the selected salt. Conla,tin~ of the cataiyst support with the salt solution can altematively be accGi"plished by other means ~pardnl to the r skilled artisan. In any case, conla,ting between the catalyst support and the selected salt places the selected salt on the surface of the catalyst support.
Treal."ent of the catalyst support is completed by ~~."o~ing the salt-treated support from the ~ueovs salt solution and drying the support with an W O96/33015 PCTrUS96/02532 air flow heated to a te"~per~ re of at least about 120~C. The dried catalyst support is then caicined, pr~6,al~!y under s~bP~ntialiy the same cor,.JiliGns asdescribed above, thereby converting the 5elected sait on the surface of the catalyst support to a cGr,~sponding basic alicali metal oxide, alicaline earth 5 metal oxide, rare earth metal oxide, or mixture tl,oreof, ~specti./eiy. A
prefellt~d basic metal oxide is a rare earth metal oxide, such as an oxide of lanthanum.
A suffident quantity of the basic metal oxide is placed on the support to reduce the acidity ll ,e~of. The amount of metal oxide placed on the cataiyst support is generally within a range between about 1.0 weight % and aioout 10.0 weight %, and p,~felabiy within a rar~e between about 2.0 wei~ht % and about 5.0 weight %.
i~reparation of the cataiyst system is imple.,.anle~l with s~l3~tion of a metal catalyst from the group consislin~ of nickel, cobalt, the platinum ~roup 15 metals, and mixtures tl,ereof. The platinum group metals as cJefine~ herein consist of platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), osmium (Os) and iridiurr (Ir). Of the metal caWysts ~ os~J herein the platinum ~roup metals are piefe,-ed, and platinum is most pr~f~..~. The 5~ led metal catalyst is placed on the prel~eale.l catalyst support by contacting the 20 pretreated catatyst support with a solution of the sGlected metal catalyst, pr~fe(al~ly in the form ot one of its salts, such as a solution of platinum chloride.
Contacting of the catalyst support with the seleute~ metal catalyst sol ~tion can be acoon,,l shed in su~ tially the same ,..anner as desc,;~ed above or, alternatively, by other means appar~nt to the skilled artisan. In any 25 case, conla~ting between the catalyst support and the sele.AeJ metal catalyst solution places the metal catalyst on the surface of the ç~ l support augmenting the metal oxide treatment. A sufficient quantity of the metal catalyst is placed on the support to enable orr~ti~o pe,h,r--.e..)ce of the resulting catalyst system in the conversion of hydroquinone to its co. .~ponding30 quinone. The amount of metal catalyst placed on the ~r~lr~ated catalyst support is generally within a range bet-.3E., about 0.01 weight % and about 3.0 weight %, and pr~ferdbly within a range between about 0.1 wei~ht % and about W O96/33015 PCTrUS96/02532 2.0 weight %. The resulting catalyst system is then dried and calcined in s~ st~ntially the same manner as desciibe J above.
The catalyst system preF~.~ in the "~nner of the pr~senl invention has specific utility in the above~lescrlbecl dehy~ Gnalion r~a~tion of the sulfur recovery process, wherein the catalyst converts a hydroquinone dissolved in the polar solvent to hydlogan gas that is recovered as a co,n",er~al product and to the corr6s~0n.iing quinone that is recycled to the H2S conversion reactor.
The following examples delllonalldle the p~ arK~ utility of the present invention, but are not to be constnued as limitin~ the scope tl,erdof.
A series of test runs are pelh,r",ed in a dehydro~enation reactor to c~ele""ine the selechvity that ditf~,e,lt c~atyst systerns exhibit in the conversion of an anthrahydroquinone to its cor,aspoi-~in~ arni-,~ inone and hy.J~u~on.
The reactor feed co--~osiliGn for all runs is pr~areJ co,..~,n~inç~ a mixture oft-butyl anthrahydroquinone (H2T8AQ) and t-butyl a,nilra~ inone (TBAQ) in a N-rnethyl-2-pyrrolidinone (NMP) solvent. The relative quantity of total quinone species (H2TBAQ and TBAQ) in the feed is 25 % by weight. The mole ratio of H2TBAQ to T8AQ in the feed is 76.0:24Ø
In each test run, the catalytic dehyd~enalion r~t~r is charged with a different catalyst system comprising a catalyst and a catalyst support. The reactor is a packed stainlsss steel tube having a diameter of 1.27 cm. The different catalyst systems are characterized below:
Catalyst Catalyst Wt % on Support Oxide Wt%C~
.System Typa .~, ~rt Ty~a ~ nn , A Pt 2.75 SjO2 La2O3 2.50 B Pt 2.75 SiO2 C Cr2O3 12 Al2O3 The silica (SiO2) type catalyst support is D~vidson ~7 having a pore volume of 1.0 cm3 and contains 99.5 % SiO2 by weiç~ht. The alumina (A~O3) type catalyst support is Norton having a pore volume of 0.57 to 0.67 cm3 and contains 99.85 % Al2O3 by weight. Each of the catalyst supports has a surface area of 260 m2/g.
Catalyst system A is a catalyst system of the pr~sent invenlion having a prel. ealed catalyst support p~pareJ in ac~ance with the manner described herein. The support is initially crushed and sieved to an av~r~e particle size of 0.56 mm. The sized support is calcinecl ovemight at a tamperature of 500~C. Lantl,an.lm oxide (La2O3) is placed on the calcined support by d~.~pN;5~ adding an ~ eous solutien of la.lt~ m nitrate (La2(NO3)3) to the support while continuously mixin~ and shaking the support, thereby producing a la"ll-~)~Jm nitrate on the support surface. The tlt~al6d support is then dried with air flow for 2 hours at 120~C and calcined ovemight at 500~C to obtain the desired lanthanum oxide~ te~ support. A platinum (Pt) catalyst is then placed on the pr~t,edled support by ~l~o,~/;3a adding an ~clueous solution of platinum chlGiilJe (PtCI~) to the pret,~dted support while continuously mixing and shaking the support. The catalyst system is dried with air flow for 2 hours at 120~C, calcined ovemi~ht at 500~C, cooled to room temperature, and stored in a ~lesi~tsr for use.
Catalyst systems B and C are prior art oalaly--l systems prepared in sub~lPnlially the same manner as cJes~-ib6~1 above, but without pret.eat",ent W O9613301S PCTrUS96/02532 of the catalyst support. The alumina eatalyst support is crushed and sieved to a particle size from 14 to 20 mesh.
The amount of catalyst system ~ ,ary~ to the packed bed of the reactor in each nun is 7.8 em~. The reaetor is ",aintained at a te""~cr~.lre betwGGn 265~C and 275~C and at a hyJ~en pressure bet-v600 430 kPa and 500 kPa.
In eaeh run the feed is retained in the dehyd~u~enatiGn reaetor for a residence time of 1 minute. The product is then removed from the reactor and analyzed to .Jet6""i,-e the degree of total H2TBAQ conversion and conversion of H2TBAQ
to TBAQ and hydro~en. The results are set forth in the table below.
TABLE OF RESULTS
Run Catalyst H2TBAQ Conv~,sion (mole%) ystem IQ~al To TR~
3 C 21 o Run 1 ~e"lûr,~ dles the enhanced pe,h,r-"ance of a cata~l system of the present invention for selectively con~e. ting H2TBAQ to TBAQ and hydrogen. The catalyst system of nun 1 has a pr~lddt~J catalyst support as compared to the prior art catalyst systems ot nuns 2 and 3 having u-lt-eate-l catalyst supports.
FXAMpl F ~
An analytical prucedure is performed on a pair of catalyst support samples to dele"-ine the relative acidities of the two sarnples. Sample 1 is an alurnina r~talyst support treated in acoor~lance with the pr.cess of the presentinvention placing lanthanum oxide on the cata~-l support. Sample 2 is an alumina catalyst support subst~ntially identieal to the ~taly~l support of Sample 1, but lac~ing a lanlhdnum oxide l,~at,-.ont.
Eaeh sample is initially conla~ 1~1 with a""-,on;a to saturate the surface thereof. The a"""onia saturated samples are then heated to drive off the adsorLeJ a"""onia, while measuring the amount of ~,....on;a d~sG,LeJ as a function of temperature by a teehnique tellll~ t~."pcrdture pru~r~,,,med W O96/33015 11 PCT~US96/02532 desorption (TPD). The desGiL.ecl ammonia from each sample is coilected in sulfuric add solutions and the solutions are titrated upon cGi"pletion of the TPD
runs to determine the total amount of deso,~ a"""~nia from each sample.
The resuits of the TPD runs are shown in the Fiç~ure, wherein a TPD
profile for each sample is ~oneral~J by plottin~ the intensty of the a"""onia signal on the y-axis (which is p,opo,tiol-al to the rate of a"""onia deso,~,lion) against te",~er~re on the x-axis. The amount of a"""onia d~50l~1 from the sample is a function of the amount of ~"I"Gn;a ~GIbed onto the sa"lpla, which in turn is a function of the acidity of the sample. Ac~,~lin~ly a sample having more ammonia .lesGibeJ tl.~re~,u.,, is relative~y more acidic than a sample having less ammonia desorbed II,er~f~ul,-.
The TPD profile of Sarnple 2 in the Figure shows that untledl~ alumina contains both weak and strong acid sites. The weak acid sites are evidenced on the TPD profile of Sample 2 by a tel",~r~ture peak around 290~C, cGr,espûnding to a ",axi-"um dasû~Jtiûn rate at this te-"pe.dture. The strong acid sites are evi~6nc6c~ on the T~D profile of Sample 2 by a pronounced shoulder center~cl around 400~C. The area under the TPD profile of Sample 2 is greater than that of Sample 1 indicating that the lladt~ alumina deso,Ls less a-",nol,ia than the u-lt~a~ecl alumina and is, ll.erefere, less acidic than the untreated alumina. Although the TPD profile of Sample 1 exhibits a temperature peak around 290~C cGr,espondi"g to the temperature peak of Sample 2 indicatin~ the pr~sence of weak acid sites on Sample 1, there are fewer such sites on Sample 1 as e~,ic;E.-c~ by a lower pea~ The TPD profile of Sample 1 also does not exhibit the shoulder centereJ around 400~C
2~ exhibited by the TPD profile of Sample 2, sug~estin~ that l.a~",enl of the alumina catalyst support in the ",anner of the pr~s~.,l inve.~tion su~sl~nliall~ reduces the number ot strong acid sites lhereon.
The rne~ ~red value of total a"",~nia deSG ~ from Sample 2 is 3.6 std cm3/g and the measured value of.total ~"., ~nia desci.l~l from Sample 1 is 2.9 std cm3/g, col-firl"ing the fi~nJings of the TPD prohles that the present treatment process favorably reduces the acidity of the alumina ~lalysl support.
CA 022l2892 l997-08-l2 W O96/33015 12 PCTrUS96/02532 FXAMPI F ~
An analytical procedure is performed on a pair of catalyst system samples to dete",i,le the relative ~d~ities of the two sarnples. The first sample is a palladium catalyst on a y-alumina support that has been prepared in accGi~ance with the p.ucess of the pl~enl invention, pr~ dlin~ the catalyst support by placinçl lanthanum oxide II,ereon. The second sample is a p~ urn catalyst on a y-alumina support subsl~- Itially ide. ,lical to the lreale~l catalyst support of the first sample, but lackin~ la.ltl.an.lm oxide. The catalyst concentration of both samples is 0.5 % by weight. The la-ltl~,um oxide concentration of the first sample is 7.0 % by weis~ht.
A ,.~tl,anol dehydl~ion le~tion is carried out in the presence of each catalyst system sarnple at 300~C and the relative rates of Ji...etll~l ether (DME) production for each sample are measured. A higher rate of DME pro~ tion indicates the prt,sence of more acid sites on the catalyst system be~Jse such sites are required for the dehyd.atiGo feaction. DME production in the presence of the first sal-lple is 1.5 mole %, while DME pro~-~ction in the presence of the second sample is 10.9 mole %. The results show that the catalyst system prepared by the p,weas of the pr6s~nl invention has subsl~nlially fewer acid sites than a c~",pa.~ble cataly~l system lacWng lanthanum oxide on the catalyst support.
While the for~oing plefe"~ e.,l~iments of the inventiol, have been desc~ e.l and shown it is u~elat~ that altematives and Ill~lific~tiGnâ such as those su~e~t~ I and others, may be made tl ,er~to and fall within the scope ~ of the present inve.ltiGn.
FXAMpl F ~
An analytical prucedure is performed on a pair of catalyst support samples to dele"-ine the relative acidities of the two sarnples. Sample 1 is an alurnina r~talyst support treated in acoor~lance with the pr.cess of the presentinvention placing lanthanum oxide on the cata~-l support. Sample 2 is an alumina catalyst support subst~ntially identieal to the ~taly~l support of Sample 1, but lac~ing a lanlhdnum oxide l,~at,-.ont.
Eaeh sample is initially conla~ 1~1 with a""-,on;a to saturate the surface thereof. The a"""onia saturated samples are then heated to drive off the adsorLeJ a"""onia, while measuring the amount of ~,....on;a d~sG,LeJ as a function of temperature by a teehnique tellll~ t~."pcrdture pru~r~,,,med W O96/33015 11 PCT~US96/02532 desorption (TPD). The desGiL.ecl ammonia from each sample is coilected in sulfuric add solutions and the solutions are titrated upon cGi"pletion of the TPD
runs to determine the total amount of deso,~ a"""~nia from each sample.
The resuits of the TPD runs are shown in the Fiç~ure, wherein a TPD
profile for each sample is ~oneral~J by plottin~ the intensty of the a"""onia signal on the y-axis (which is p,opo,tiol-al to the rate of a"""onia deso,~,lion) against te",~er~re on the x-axis. The amount of a"""onia d~50l~1 from the sample is a function of the amount of ~"I"Gn;a ~GIbed onto the sa"lpla, which in turn is a function of the acidity of the sample. Ac~,~lin~ly a sample having more ammonia .lesGibeJ tl.~re~,u.,, is relative~y more acidic than a sample having less ammonia desorbed II,er~f~ul,-.
The TPD profile of Sarnple 2 in the Figure shows that untledl~ alumina contains both weak and strong acid sites. The weak acid sites are evidenced on the TPD profile of Sample 2 by a tel",~r~ture peak around 290~C, cGr,espûnding to a ",axi-"um dasû~Jtiûn rate at this te-"pe.dture. The strong acid sites are evi~6nc6c~ on the T~D profile of Sample 2 by a pronounced shoulder center~cl around 400~C. The area under the TPD profile of Sample 2 is greater than that of Sample 1 indicating that the lladt~ alumina deso,Ls less a-",nol,ia than the u-lt~a~ecl alumina and is, ll.erefere, less acidic than the untreated alumina. Although the TPD profile of Sample 1 exhibits a temperature peak around 290~C cGr,espondi"g to the temperature peak of Sample 2 indicatin~ the pr~sence of weak acid sites on Sample 1, there are fewer such sites on Sample 1 as e~,ic;E.-c~ by a lower pea~ The TPD profile of Sample 1 also does not exhibit the shoulder centereJ around 400~C
2~ exhibited by the TPD profile of Sample 2, sug~estin~ that l.a~",enl of the alumina catalyst support in the ",anner of the pr~s~.,l inve.~tion su~sl~nliall~ reduces the number ot strong acid sites lhereon.
The rne~ ~red value of total a"",~nia deSG ~ from Sample 2 is 3.6 std cm3/g and the measured value of.total ~"., ~nia desci.l~l from Sample 1 is 2.9 std cm3/g, col-firl"ing the fi~nJings of the TPD prohles that the present treatment process favorably reduces the acidity of the alumina ~lalysl support.
CA 022l2892 l997-08-l2 W O96/33015 12 PCTrUS96/02532 FXAMPI F ~
An analytical procedure is performed on a pair of catalyst system samples to dete",i,le the relative ~d~ities of the two sarnples. The first sample is a palladium catalyst on a y-alumina support that has been prepared in accGi~ance with the p.ucess of the pl~enl invention, pr~ dlin~ the catalyst support by placinçl lanthanum oxide II,ereon. The second sample is a p~ urn catalyst on a y-alumina support subsl~- Itially ide. ,lical to the lreale~l catalyst support of the first sample, but lackin~ la.ltl.an.lm oxide. The catalyst concentration of both samples is 0.5 % by weight. The la-ltl~,um oxide concentration of the first sample is 7.0 % by weis~ht.
A ,.~tl,anol dehydl~ion le~tion is carried out in the presence of each catalyst system sarnple at 300~C and the relative rates of Ji...etll~l ether (DME) production for each sample are measured. A higher rate of DME pro~ tion indicates the prt,sence of more acid sites on the catalyst system be~Jse such sites are required for the dehyd.atiGo feaction. DME production in the presence of the first sal-lple is 1.5 mole %, while DME pro~-~ction in the presence of the second sample is 10.9 mole %. The results show that the catalyst system prepared by the p,weas of the pr6s~nl invention has subsl~nlially fewer acid sites than a c~",pa.~ble cataly~l system lacWng lanthanum oxide on the catalyst support.
While the for~oing plefe"~ e.,l~iments of the inventiol, have been desc~ e.l and shown it is u~elat~ that altematives and Ill~lific~tiGnâ such as those su~e~t~ I and others, may be made tl ,er~to and fall within the scope ~ of the present inve.ltiGn.
Claims (24)
1. A process for preparing a dehydrogenation catalyst system to convert a hydroquinone to a corresponding quinone and hydrogen comprising:
selecting a catalyst support from the group consisting of alumina and silica;
placing a sufficient quantity of a rare earth metal oxide on said catalyst support to reduce the acidity thereof;
selecting a catalyst from the group consisting of nickel, cobalt, the platinum group metals, and mixtures thereof; and placing said catalyst on said catalyst support to form a catalyst system.
selecting a catalyst support from the group consisting of alumina and silica;
placing a sufficient quantity of a rare earth metal oxide on said catalyst support to reduce the acidity thereof;
selecting a catalyst from the group consisting of nickel, cobalt, the platinum group metals, and mixtures thereof; and placing said catalyst on said catalyst support to form a catalyst system.
2. The process of claim 1 wherein said rare earth metal oxide is placed on said catalyst support by contacting said catalyst support with a corresponding rare earth metal salt in solution.
3. The process of claim 1 wherein said rare earth metal oxide is lanthanum oxide.
4. The process of claim 2 wherein said corresponding rare earth metal salt is lanthanum nitrate.
5. The process of claim 1 wherein said catalyst is platinum.
6. The process of claim 2 further comprising calcining said catalyst support after contacting said catalyst support with said rare earth metal salt.
7. The process of claim 1 further comprising calcining said catalyst support after placing said catalyst thereon.
8. The process of claim 1 wherein said catalyst is placed on said catalyst support by contacting said catalyst support with a solution of a corresponding catalyst metal salt.
9. A process for preparing a dehydrogenation catalyst system used to convert a hydroquinone to a corresponding quinone and hydrogen comprising:
selecting a catalyst support from the group consisting of alumina and silica;
placing a sufficient quantity of a metal oxide on said catalyst support to reduce the acidity thereof by contacting said catalyst support with a corresponding metal salt in solution and calcining said catalyst support to convert said corresponding metal salt to said metal oxide, wherein said metal oxide is selected from the group consisting of rare earth metal oxides, alkaline earth metal oxides, alkali metal oxides, and mixtures thereof, and said corresponding metal salt is selected from the group consisting of rare earth metal salts, alkaline earth metal salts, alkali metal salts, and mixtures thereof;
selecting a catalyst from the group consisting of cobalt, nickel, the platinum group metals, and mixtures thereof; and placing said catalyst on said catalyst support by contacting said catalyst support with a solution of a corresponding catalyst metal salt to form a catalyst system.
selecting a catalyst support from the group consisting of alumina and silica;
placing a sufficient quantity of a metal oxide on said catalyst support to reduce the acidity thereof by contacting said catalyst support with a corresponding metal salt in solution and calcining said catalyst support to convert said corresponding metal salt to said metal oxide, wherein said metal oxide is selected from the group consisting of rare earth metal oxides, alkaline earth metal oxides, alkali metal oxides, and mixtures thereof, and said corresponding metal salt is selected from the group consisting of rare earth metal salts, alkaline earth metal salts, alkali metal salts, and mixtures thereof;
selecting a catalyst from the group consisting of cobalt, nickel, the platinum group metals, and mixtures thereof; and placing said catalyst on said catalyst support by contacting said catalyst support with a solution of a corresponding catalyst metal salt to form a catalyst system.
10. The process of claim 9 further comprising calcining said catalyst system after placing said catalyst on said catalyst support.
11. A process for treating a catalyst support of a catalyst used to convert a hydroquinone to a corresponding quinone and hydrogen comprising:
selecting a catalyst support from the group consisting of alumina and silica; and placing a sufficient quantity of a rare earth metal oxide on said catalyst support to reduce the acidity thereof.
selecting a catalyst support from the group consisting of alumina and silica; and placing a sufficient quantity of a rare earth metal oxide on said catalyst support to reduce the acidity thereof.
12. The process of claim 11 wherein said rare earth metal oxide is placed on said catalyst support by contacting said catalyst support with a corresponding rare earth metal salt in solution.
13. The process of claim 11 wherein said rare earth metal oxide is lanthanum oxide.
14. The process of claim 12 wherein said corresponding rare earth metal salt is lanthanum nitrate.
15. The process of claim 12 further comprising calcining said catalyst support after contacting said catalyst support with said corresponding rare earth metal salt.
16. A dehydrogenation catalyst system comprising:
a catalyst support having a porous surface, said catalyst support selected from the group consisting of alumina and silica;
a rare earth metal oxide positioned on said surface of said catalyst support in a quantity sufficient to reduce the acidity thereof; and a catalyst positioned on said surface of said catalyst support, said catalyst selected from the group consisting of cobalt, nickel, the platinum group metals, and mixtures thereof.
a catalyst support having a porous surface, said catalyst support selected from the group consisting of alumina and silica;
a rare earth metal oxide positioned on said surface of said catalyst support in a quantity sufficient to reduce the acidity thereof; and a catalyst positioned on said surface of said catalyst support, said catalyst selected from the group consisting of cobalt, nickel, the platinum group metals, and mixtures thereof.
17. The catalyst system of claim 16 wherein said rare earth metal oxide is lanthanum oxide.
18. The catalyst system of claim 16 wherein said catalyst is platinum.
19. A process for catalytically converting a hydroquinone to a corresponding quinone and hydrogen comprising:
selecting a catalyst support from the group consisting of alumina and silica;
placing a sufficient quantity of a metal oxide selected from the group consisting of rare earth metal oxides, alkaline earth metal oxides, alkali metal oxides, and mixtures thereof, on said catalyst support to reduce the acidity thereof;
selecting a catalyst from the group consisting of nickel, cobalt, the platinum group metals, and mixtures thereof;
placing said catalyst on said catalyst support to form a catalyst system;
converting a hydroquinone in the presence of said catalyst system to hydrogen and a corresponding quinone of said hydroquinone.
selecting a catalyst support from the group consisting of alumina and silica;
placing a sufficient quantity of a metal oxide selected from the group consisting of rare earth metal oxides, alkaline earth metal oxides, alkali metal oxides, and mixtures thereof, on said catalyst support to reduce the acidity thereof;
selecting a catalyst from the group consisting of nickel, cobalt, the platinum group metals, and mixtures thereof;
placing said catalyst on said catalyst support to form a catalyst system;
converting a hydroquinone in the presence of said catalyst system to hydrogen and a corresponding quinone of said hydroquinone.
20. The process of claim 19 wherein said metal oxide is a rare earth metal oxide.
21. The process of claim 19 wherein said hydroquinone is selected from the group consisting of anthrahydroquinones, naphthahydroquinones, benzohydroquinones, and mixtures thereof.
22. A process for producing sulfur and hydrogen from hydrogen sulfide gas comprising:
reacting hydrogen sulfide gas with a quinone to produce sulfur and a corresponding hydroquinone of said quinone;
recovering said sulfur; and regenerating said quinone from said corresponding hydroquinone by contacting said hydroquinone with a catalyst system prepared by the steps comprising; selecting a catalyst support from the group consisting of alumina and silica; placing a sufficient quantity of a metal oxide selected from the group consisting of rare earth metal oxides, alkaline earth metal oxides, alkali metal oxides, and mixtures thereof, on said catalyst support to reduce the acidity thereof; selecting a catalyst from the group consisting of nickel, cobalt, the platinum group metals, and mixtures thereof, and placing said catalyst on said catalyst support to form said catalyst system.
reacting hydrogen sulfide gas with a quinone to produce sulfur and a corresponding hydroquinone of said quinone;
recovering said sulfur; and regenerating said quinone from said corresponding hydroquinone by contacting said hydroquinone with a catalyst system prepared by the steps comprising; selecting a catalyst support from the group consisting of alumina and silica; placing a sufficient quantity of a metal oxide selected from the group consisting of rare earth metal oxides, alkaline earth metal oxides, alkali metal oxides, and mixtures thereof, on said catalyst support to reduce the acidity thereof; selecting a catalyst from the group consisting of nickel, cobalt, the platinum group metals, and mixtures thereof, and placing said catalyst on said catalyst support to form said catalyst system.
23. The process of claim 22 wherein said metal oxide is a rare earth metal oxide.
24. The process of claim 22 wherein said quinone is selected from the group consisting of anthraquinones, naphthaquinones, benzoquinones, and mixtures thereof.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US42342295A | 1995-04-18 | 1995-04-18 | |
| US423,422 | 1995-04-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2212892A1 true CA2212892A1 (en) | 1996-10-24 |
Family
ID=23678853
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002212892A Abandoned CA2212892A1 (en) | 1995-04-18 | 1996-02-22 | Pretreatment of catalyst support to enhance catalytic dehydrogenation of a hydroquinone |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU5173396A (en) |
| CA (1) | CA2212892A1 (en) |
| WO (1) | WO1996033015A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19908394A1 (en) * | 1999-02-26 | 2000-08-31 | Degussa | Catalyst material and process for its manufacture |
| US8105969B2 (en) * | 2008-12-29 | 2012-01-31 | Fina Technology Inc. | Catalyst with an ion-modified binder |
| KR102563207B1 (en) * | 2018-10-31 | 2023-08-02 | 에스케이이노베이션 주식회사 | Cobalt-based Single-atom Dehydrogenation Catalysts and Method for Producing Corresponding Olefins from Paraffins Using the Same |
| EP3928864A1 (en) | 2020-06-25 | 2021-12-29 | SK Innovation Co., Ltd. | Cobalt-based single-atom dehydrogenation catalysts having improved thermal stability and method for producing olefins from corresponding paraffins by using the same |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3993572A (en) * | 1972-08-04 | 1976-11-23 | Engelhard Minerals & Chemicals Corporation | Rare earth containing catalyst composition |
| US4592905A (en) * | 1985-01-14 | 1986-06-03 | Marathon Oil Company | Conversion of hydrogen sulfide to sulfur and hydrogen |
| US5107003A (en) * | 1990-03-18 | 1992-04-21 | Eastman Kodak Company | Preparation of quinones by the ceric-catalyzed oxidation of aromatic diols |
| US5439859A (en) * | 1992-04-27 | 1995-08-08 | Sun Company, Inc. (R&M) | Process and catalyst for dehydrogenation of organic compounds |
-
1996
- 1996-02-22 CA CA002212892A patent/CA2212892A1/en not_active Abandoned
- 1996-02-22 WO PCT/US1996/002532 patent/WO1996033015A1/en active Application Filing
- 1996-02-22 AU AU51733/96A patent/AU5173396A/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| MX9706862A (en) | 1997-11-29 |
| WO1996033015A1 (en) | 1996-10-24 |
| AU5173396A (en) | 1996-11-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4780552A (en) | Preparation of furan by decarbonylation of furfural | |
| US3515514A (en) | Production of hydrogen containing gases | |
| CA1050051A (en) | Process for the production of unsaturated hydrocarbons | |
| EP1160196B1 (en) | Catalyst and process for the direct synthesis of hydrogen peroxide | |
| US4623668A (en) | Preparation of methanol | |
| JPH05330802A (en) | Production of ammonia-cracked gas and production of hydrogen | |
| CN108435171B (en) | Preparation method of bimetallic Pt-Bi catalyst and method for preparing DHA (docosahexaenoic acid) by selectively catalyzing and oxidizing glycerol | |
| US8057572B2 (en) | Metal recovery | |
| US5395976A (en) | Process for the preparation of a mixture of cyclohexanone and cyclohexanol | |
| US2747970A (en) | Purification of commercial hydrogen | |
| EP0533228B1 (en) | Process for the activation of a catalyst | |
| CA2212892A1 (en) | Pretreatment of catalyst support to enhance catalytic dehydrogenation of a hydroquinone | |
| US5146013A (en) | Process for the production of chloroform from carbon tetrachloride, catalytic compositions and process for obtaining them | |
| CN117623327A (en) | Ni modified micropore-mesoporous molecular sieve and preparation method and application thereof | |
| US7524786B2 (en) | Regeneration of synthesis gas catalysts | |
| US2939883A (en) | Dehydrogenation of alcohols to | |
| EP0467176B1 (en) | Process for regenerating inactive and poisoned platinum catalyst | |
| US5872075A (en) | Catalyst for oxidation of hydrogen, method for selective oxidation of hydrogen, and method for dehydrogenation of hydrocarbon | |
| US3937735A (en) | Process for the preparation of cyclohexanone | |
| EP0209980B1 (en) | Syngas conversion | |
| US3998936A (en) | Process for regenerating hydrogenation catalyst activity in hydrogen peroxide synthesis | |
| US3932536A (en) | Process for preparing hydroxydiphenyl | |
| JP2000143216A (en) | Production of hydrogen peroxide | |
| US8894960B2 (en) | Process for removing NO and N2O from gas mixtures | |
| JP3876682B2 (en) | Nitric oxide production method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |