Patent Application: US-201113157455-A

Abstract:
the application describes a process where methane or any short chained hydrocarbon could be catalytically coupled with an oxygenate to dehydrate and produce a deoxygenated hydrocarbon . the presence of oxygen in biomass derivatives adversely affects its ability to be further processed into hydrocarbon fuels because the resulting water poisons many catalysts found in petrochemical refineries . while commonly used hydrodeoxygenation methods require expensive hydrogen to instigate deoxygenation , the present process uses short chained hydrocarbons to instigate hydrodeoxygenation .

Description:
studies on concurrent co - processing of methane with glucose with the target of producing liquid hydrocarbon fuels have demonstrated that it is possible to remove oxygen from oxygenates without direct intervention of hydrogen gas . using a platinized zsm - 5 bifunctional catalyst , it was demonstrated that methane could be directly coupled with oxygen in oxygenates producing water and carbon dioxide . the constituents of the remainder of the product stream were effusive amounts of gasoline range hydrocarbons . the current biomass - to - hydrocarbon technologies ( for example , pyrolysis of biomass followed by upgrading of resultant bio - oil ) involve hydrodeoxygenation of biomass - derived oxygenates , which consumes tremendous amounts of hydrogen and therefore impact the economy and sustainability of biomass - derived liquid hydrocarbon fuels . present experiments indicate that it is possible to replace hydrogen with hydrogen - rich , less expensive , and readily available methane to directly deoxygenate bio - based liquids for synthetic fuels production . unpromoted hzsm - 5 cannot activate methane . however , unpromoted or promoted hz sm - 5 can activate and aromatize oxygenates to a hydrocarbon stream that primarily consists of benzene , toluene , ethyl benzene and xylenes ( btex ) [ 17 ]. similarly , hzsm - 5 promoted with metals can aromatize methane [ 18 - 22 ]. a direct result of methane aromatization is the generation of surplus hydrogen that stays adsorbed in the catalyst matrix and would end up as molecular h 2 if not utilized . the initial idea was to harness this surplus h for deoxygenating oxygenates via dehydration since excessive coking instantaneously shuts down the catalyst if oxygenate deoxygenation is carried out with limited h 2 . therefore , a hydrogen generating reaction was kinetically coupled with a hydrogen consuming reaction on a single catalyst surface . the first set of experiments consisted of pyrolyzing : 1 ) methane ; 2 ) glucose and 3 ) a mixture of glucose and methane ( all consisting of equivalent carbon composition ) over platinized zsm - 5 . the experiments were carried out in a cds 5200 pyroprobe that had an inline gcms for product analysis . remarkable changes to product composition where observed when glucose was aromatized in the presence of methane . as seen in fig1 , introduction of methane remarkably increased the hydrocarbon yields when glucose was aromatized in the presence of methane as compared to when they were aromatized individually . the furfural ( an oxygenated product ) yield was also reduced when glucose was aromatized in the presence of methane . these results suggests that one or more of the following reactions can occur at the catalyst surface : in one possible coupling reaction ( fig2 ), the hydrogen gas formed during methane steam reforming serves as an ingredient for oxygenated pyrolytic vapor aromatization . water formed during oxygenate aromatization will serve as an ingredient for methane steam reforming . in such a scenario , the ultimate products of the reaction are hcs and co 2 . in another concurrently occurring reaction , hydrogen - rich methane is aromatized to produce btex , hcs and h 2 . oxygenates will utilize this hydrogen and aromatize removing oxygen in the form of water ( dehydration ). in one embodiment , this reaction progresses according to the general reaction scheme shown in fig3 . a third possible reaction could occur in the presence of a metal catalyst such that ch 4 would activate to chx and — h moieties . the — h moieties help the dehydration of oxygenates while the chx moieties directly couple with the oxygen deficient sites of oxygenates propagating to btex . in order to verify above premises , 13 c and 2 h ( d — deuterium ) isotope labeled compounds were used during subsequent studies . to determine whether protons from methane actually end up in the deoxygenated products 12 c - labeled glucose and cd 4 ( duterized - methane ) were used . as expected , when 12 c glucose alone was pyrolysed and passed through the catalyst , 100 % of the benzene produced was with a molecular weight of 78 amu . this is depicted as a green bar in the mass - abundance curve generated in the mass spectrum ( fig4 ). when cd 4 was used alone the most abundant molecule ( blue bars ) had a mass of 84 amu , indicating that all hydrogen vacancies are filled with deuterium . however , when cd 4 was co - processed with 12 c glucose , depending on the level of cd 4 activation , benzene structures with a range of molecular weights were observed . for example , in the likely event that the catalyst did not fully activate cd 4 , benzene with partially deuterized ring structure as shown in fig4 with corresponding molecular weights and abundance levels were observed ( red bars ). this experiment clearly proves that protons from methane actually are transferred to benzene and that methane actually participates in the deoxygenation reaction . the next step focused on finding out where the carbon atoms from methane ended up during glucose deoxygenation . this is crucial since glucose itself has six carbons and it is likely for all the carbon atoms in glucose to end up in the respective benzene structure ( although it was determined that hydrogen atoms do transfer from methane into benzene ). also , it is likely that carbon atoms from methane help in oxygen abstraction from glucose by forming co 2 instead of h 2 o ( which would be partly disadvantageous since formation of co 2 would result in losing valuable carbon that ideally should have ended up in hc product stream ). to confirm this , 13 c - labeled glucose and regular 12 c methane was used during a series of coupling experiments . the benzene produced when pure 13 c - labeled glucose was used had a molecular weight of 84 amu . in case of carbon coupling , 12 c from methane should transfer to the benzene structure reducing the molecular weight of benzene proportional to the number of carbon atoms transferred from methane . when pure 13 c - labeled glucose was used , the resultant mass spectrum pertinent to benzene consisted of a series of fragments as seen in fig5 . however , when 13 c - labeled glucose was co - processed with 12 c methane , the relative abundance of the fragments having a molecular weight less than 84 amu increased consistently . since the relative abundance of each fragment for a given molecule is constant irrespective of its concentration , it is quite clear from fig5 that the increase in relative abundance ( shown in green ) is due to the transfer of 12 c that was originally in methane to benzene that is predominantly comprised of 13 c that originally came for glucose . the experiment also confirms that the aromatization reactions that occur are not two independent reactions ( i . e ., methane aromatization and glucose aromatization ) but are two interdependent reactions . these results are unprecedented in biomass to hydrocarbon biofuels research . the use of hydrogen - rich naturally occurring alkanes as hydrogen carriers and the use of these alkanes over bifunctional shape - selective zeolite catalysts is a departure from existing approaches and have the potential to have a transformative impact on hydrodeoxygenation of biomass for fuels . these results also expose the possibility of co - processing the two most abundant hydrocarbon resources ( coal and natural gas ) to produce liquid fuels . preliminary studies were conducted to test the hypothesis that methane can be coupled with biomass pyroltic vapor oxygenates to deoxygenate into hydrocarbons over an appropriate catalyst . preliminary data demonstrates the feasibility of this concept . from the product spectrum that was produced when selected model oxygenate methanol was directly pyrolyzed ( via a cds high pressure pyroprobe ) to a gcms in the presence of a dehydration catalyst ( zsm - 5 , si : al = 40 ), it was evident that effusive amounts of aromatic ( gasoline range benzenes , toleuenes and xylenes ) and btex hydrocarbons ( fig6 , fig7 , and fig8 , respectfully ) were being produced . the results of methanol aromatization with zsm - 5 ( si / al : 40 ) under varying pressure is depicted for benzene ( fig9 ), toluene ( fig1 ), and xylenes ( fig1 ). it is evident that at atmospheric pressure , btex formation peaks around 700 ° c . carrying out the reaction at elevated pressures provides a dramatic increase of aromatic hydrocarbon formation that peaked around 100 psi . these studies were carried out in a pressurizable pyroprobe reactor that was directly coupled to a gc with duel detectors ( mass spectrometer ( ms ) and flame ionization detectors ( fid )). to verify the effect of methane on the aromatization reaction , methane , methanol and mixtures of methane and methanol were pyrolyzed to the gcms in identical experiments : ( i . e . the # of carbon atoms introduced into the reaction chamber at a give time frame was constant , at atmospheric pressure ). results of this study are depicted in fig9 for benzene , fig1 for toluene , and fig1 for xylenes . it was intriguing to note that introduction of methane ( the hydrogen - rich moiety ) onto methanol ( the oxygen - rich moiety ) increased c - 7 ( toluene ) and c - 8 ( xylenes ) yields significantly as compared to introducing any of the reactants alone . this increase was evident throughout the temperatures tested . although a reduction of benzene yield was observed , ( based on literature support ) this reduction is believed to be due to the methylation of benzene into a higher hc . preliminary data indicates that methane could be used as a direct hydrogen donor for deoxygenating oxygenates instead of using h 2 ( gas ). based on these observations , three possible reaction pathways are provided : 1 ) zsm - 5 will dehydroaromatize ch 3 oh to btex and resultant h 2 o will act as an ingredient for the ch 4 steam reforming reaction producing h 2 and co 2 . h 2 will assist in the concurrent ch 3 oh dehydration reaction . 2 ) in the acidic sites of zsm - 5 , ch 4 will aromatize into btex and the resultant h 2 will assist in dehydration of ch 3 oh to btex . 3 ) ch 4 will activate to chx and — h moieties . the — h moieties will help dehydration of oxygenates . chx moieties will directly couple with the oxygen deficient site of the methanol and propagate to btex . it is to be understood that while the invention has been described in conjunction with the detailed description thereof , the foregoing description is intended to illustrate and not limit the scope of the invention , which is defined by the scope of the appended claims . other aspects , advantages , and modifications are within the scope of the following claims . 1 . klass , d . l . 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