Following our previous report on the selective transformation of cellulose to ethylene glycol (EG) over a binary catalyst composed of tungstic acid and Ru/C, we herein report a new low‐cost but more ...effective binary catalyst by using Raney nickel in place of Ru/C (Raney Ni+H2WO4). In addition to tungstic acid, other W compounds were also investigated in combination with Raney Ni. The results showed that the EG yield depended on the W compound: H4SiW12O40<H3PW12O40<WO3<H2WO4, but all the investigated W compounds were selective towards EG. Moreover, both WO3 and H2WO4 were dissolved partially under the reaction conditions and transformed into HxWO3, which is the genuinely active species for the CC bond breakage of cellulose. This result further confirmed that the reaction that involves the selective breakage of the CC bonds of cellulose with W species is homogenous. Among various binary catalysts, the combination of Raney Ni and H2WO4 gave the highest yield of EG (65 %), which could be attributed to the high activity of Raney Ni for hydrogenation and its inertness for the further degradation of EG. Moreover, Raney Ni+H2WO4 showed good reusability; it could be reused at least 17 times without any decay in the EG yield, which shows its great potential for industrial applications.
Team work: A new low‐cost and effective catalyst composed of Raney Ni and tungstic acid is developed for ethylene glycol production from cellulose. It gives rise to yields of ethylene glycol up to 65 % and can be reused more than 17 times, which shows the great potential of this new process for the industrial application.
MoS
2
supported noble metal catalysts were used for the catalytic conversion of terahydrofurfuryl alcohol (THFA) to 1,5-pentanediol (1,5-PDO) and its derivate tetrahydropyrane (THP). Over the optimal ...4%Pt/MoS
2
-FR catalyst, 75.8% overall selectivity (35.4% to 1,5-PDO and 40.4% to THP) and 63.7% conversion of 5 wt% THFA solution were obtained after 8 h reaction at 250 °C. The catalyst showed stable catalytic performance in five-cycle reactions, demonstrating the robustness of Pt/MoS
2
under the harsh hydrothermal and hydrogenation conditions. A variety of characterizations, including CO-DRIFTS, HRTEM, H
2
-TPR, Raman spectroscopy and XPS revealed that typical behavior of strong metal-support interaction (SMSI) existed between Pt and MoS
2
, largely caused by the coverage of MoS
2
over Pt and rarely reported previously. The Pt/MoS
2
had intact structure under the harsh conditions thanks to the SMSI and chemical stability of MoS
2
. The acidity of Pt/MoS
2
was negligible, and the active sites for the reaction were attributed to Pt and the Mo sites interacting closely on the catalysts. The reaction pathway was proposed according to the product distributions and the results of conditional experiments.
Graphic Abstract
A series of Ni‐promoted W2C catalysts was prepared by means of a post‐impregnation method and evaluated for the catalytic conversion of cellulose into ethylene glycol (EG). Quite different from our ...previously reported Ni–W2C/AC catalysts, which were prepared by using the co‐impregnation method, the introduction of Ni by the post‐impregnation method did not cause catalyst sintering, but resulted in redispersion of the W component, which was identified and characterized by means of XRD, TEM, and CO chemisorption. The highly dispersed Ni‐promoted W2C catalyst was very active and selective in cellulose conversion into EG, with a 100 % conversion of cellulose and a 73.0 % yield in EG. The underlying reason for the enhanced catalytic performance was most probably the significantly higher dispersion of active sites on the catalyst.
Disappearing cellulose: Highly dispersed Ni‐promoted W2C catalysts have been prepared by a post‐impregnation method and found to be very active and selective for cellulose conversion into ethylene glycol (EG). Over Ni–(W2C/AC) catalyst, total cellulose conversion with a high EG yield has been achieved. The underlying reason for the enhanced catalytic performance is most probably the significantly higher dispersion of active sites on the catalyst.
A series of Ni‐promoted W2C/activated carbon (AC) catalysts were investigated for the catalytic conversion of Jerusalem artichoke tuber (JAT) under hydrothermal conditions and hydrogen pressure. Even ...a small amount of Ni could greatly promote the conversion of JAT to 1,2‐propylene glycol (1,2‐PG), whereas the pure W2C/AC catalyst resulted in the selective formation of acetol. The product distribution profiles involving the reaction temperature, time, and H2 pressure indicated that 1,2‐PG formed as a result of acetol hydrogenation, which was catalyzed by Ni. Thus, there was a synergy between W2C and Ni, and the best performance yielded 38.5 % of 1,2‐PG over a 4 % Ni–20 % W2C/AC catalyst at 245 °C, 6 MPa H2, and 80 min. To understand the reaction process, some important intermediates, such as inulin, fructose, acetol, glyceraldehyde, and 1,3‐dihydroxyacetone, were used as the feedstock. Based on the product distributions derived from these intermediates, a reaction pathway was proposed, where JAT was first hydrolyzed into a mixture of fructose and glucose under the catalysis of H+, then the sugars underwent a retro‐aldol reaction followed by hydrogenation catalyzed by Ni–W2C.
Down to the roots with Ni: By using a combination of nickel and tungsten carbide supported on activated carbon, it is possible to convert Jerusalem artichoke tuber (JAT), a fructose‐based biomass that can be used as a raw material without any pretreatment, selectively into 1,2‐propylene glycol and ethylene glycol. A reasonable reaction pathway is suggested based on analysis of the product distribution under different reaction conditions and use of different feedstocks.
High-performance Cu catalysts were developed for the selective hydrogenation of γ-butyrolactone (GBL) to 1,4-butanediol (BDO). Among the various catalysts prepared by ammonia evaporation (AE) and ...impregnation (IM) methods with silica or MFI zeolite supports, the 5% Cu-SiO2-AE catalyst was the best one. It exhibited 95% selectivity for BDO and 71% conversion of GBL after 2–8 h reaction at 200 °C and 4 MPa H2, with high stability in five-cycle runs. Comprehensive characterizations showed that the AE method favored generating nano Cu particles with an average size of 2.9 nm on the 5% Cu-SiO2-AE catalyst. The silica support derived from a sol demonstrated an advantage over the MFI zeolite in the preparation of a highly dispersed and stable Cu catalyst, in view of its anti-sintering and robust composition of Cu0, Cu+, and Cu2+ in the cycling operation. The reaction pathways for GBL to BDO over the Cu catalysts were found to commonly involve reversible reactions of hydrogenation and dehydrogenation, along with subsequent dehydration to form THF. The high performance of the Cu catalysts in the conversion of GBL to BDO was attributed to the high dispersion of Cu, the presence of stable active sites, and fewer strong acid sites in the catalyst.
In the current paper we present a combined catalytic and surface science studies to evaluate the utilization of carbide catalysts for the conversion of cellulose to polyols, especially to ethylene ...glycol (EG). Based on catalytic studies over a W
2C catalyst, the EG yield has been optimized by varying H
2 pressure, reaction temperature and time. The catalytic performance has been compared for several types of supported catalysts, including tungsten carbides, molybdenum carbides and platinum on different supports. Among all the catalysts, tungsten carbide supported on activated carbon, W
2C/AC, shows the highest EG yield, which is further enhanced to 61% with the promotion of Ni. The corresponding surface science studies indicate that the enhanced EG yield is at least partially due to a weaker bonding between EG and Ni-promoted tungsten carbide surface.
A high-performance Pt catalyst supported on SBA-15 was developed for furfural decarbonylation. Compared to Pt catalysts loaded on microporous DeAl-Hbeta zeolite and hierarchical micro-mesoporous MFI ...nanosheet (NS) materials, the 1%Pt/SBA-15 catalyst afforded notably higher activity, furan selectivity and stability owing to the negligible acid sites and proper mesopores on the SBA-15 support. Among a set of 1%Pt/SBA-15 catalysts bearing Pt nanoparticles (NPs) with sizes of 2.4–4.3 nm, the catalyst with 3.7 nm Pt NPs afforded the highest furan selectivity. Over the optimal catalyst, 88.6% furan selectivity and ca. 90% furfural conversion were obtained at 573 K and a high weight hourly space velocity (WHSV) of 16.5 h−1. Moreover, the reaction temperatures at 440–573 K and the ratios of H2 to furfural at 0.79–9.44 did not affect the reaction selectivity notably, showing that the reaction over 1%Pt/SBA-15 can be conducted over a wide range of conditions. The catalyst was stable under the harsh reaction conditions and lasted for 90 h without significant deactivation, demonstrating the superior property of SBA-15 as a catalyst support for furfural decarbonylation.
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