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Catalytic Conversion of Biomass-Derived Oxygenates to alpha,o-Diols
Başlık:
Catalytic Conversion of Biomass-Derived Oxygenates to alpha,o-Diols
Yazar:
Barnett, Kevin J., author.
ISBN:
9780355990997
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (170 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.
Advisors: George W. Huber Committee members: James A. Dumesic; Ive Hermans; Manos Mavrikakis; Thatcher W. Root.
Özet:
Commodity chemical production from lignocellulosic biomass resources has the potential to sustainably replace petroleum-derived chemicals and to improve the economic feasibility of biofuels production. One class of chemicals of interest are alpha,&ohgr;-diols, particularly those with four, five, and six carbon atoms (C4-C6): 1,4-butanediol (1,4-BD), 1,5-pentanediol (1,5-PD) and 1,6-hexanediol (1,6-HD), respectively. These alpha,&ohgr;-diols are primarily used as monomers in the synthesis of polycarbonate polyols, polyester polyols, and polyurethanes and represent a combined $7 billion annual market that is growing at 7% per year.
C5 and C6 alpha,&ohgr;-diols were synthesized from biomass-derived oxygenates tetrahydrofurfuryl alcohol (THFA) and tetrahydropyran-2-methanol (THP2M), respectively. A three-step Dehydration-Hydration-Hydrogenation (DHH) pathway form THFA was shown to decrease catalyst costs by >50x and non-feedstock production costs by 6.6x versus the direct hydrogenolysis of THFA over oxophilically-promoted noble metal catalysts (e.g. RhRe). Here, 1,5-PD is produced via vapor-phase Dehydration of THFA to dihydropyran (DHP), Hydration of DHP to 2-hydroxytetrahydropyran (2-HTHP) in water, and Hydrogenation of the ring-opened tautomer of 2-HTHP, 5-hydroxyvaleraldehyde (5HVal), to 1,5-PD. The DHH pathway afforded 87% overall yields of 1,5-PD from THFA.
The keys to the high yields and low costs achieved in the DHH pathway were the high thermodynamic favorability to desired products and increased reactivities of the reaction intermediates. Gas-phase THFA dehydration yielded 90% yield to DHP over a gamma-Al2O3 catalyst due to the high thermodynamic favorability to the DHP product. DHP hydrated to 2-HTHP at over six orders of magnitude faster than cyclohexene due to the formation of a very stable oxocarbenium intermediate. The cyclic hemiacetal 2-HTHP hydration product spontaneously tautomerizes to its ring-opened aldehyde form, 5HVal, in solution, leading to a ~50:50 mixture of 2-HTHP:5Hval at 120°C. Hydrogenation of the aldehyde group (at 120°C) enables the use of monometallic catalysts and 80x increased reaction rates versus the direct hydrogenolysis of THFA.
Hydration-hydrogenation chemistry was applied to C4 and C6 feedstocks to produce 1,4-BD and 1,6-HD, respectively. The DHH chemistry applied to the analogous C6 route yielded 34% 1,6-HD from biomass-derived tetrahydropyran-2-methanol. 2,5-dihydrofuran (C4) was converted to 1,4-BD in 82% yields in a single batch reaction step over solid-acid hydration and metal hydrogenation catalysts. gamma-Butyrolactone (GBL) made from biomass-derived furfural was hydrogenated to 1,4-BD at >95% yields over bimetallic CuCo/TiO2 catalyst. GBL hydrogenation rates were improved by 2.5x over monometallic Co and 20x over monometallic Cu catalysts, respectively, when employing a bimetallic CoCu/TiO2 catalyst with a 90:10 Co:Cu ratio.
Notlar:
School code: 0262
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