Confined dual Lewis acid centers for selective cascade C-C coupling and deoxygenation.

The selective formation of C-C bonds, coupled with effective removal of oxygen, plays a crucial role in the process of upgrading biomass-derived oxygenates into fuels and chemicals. However, co-feeding reactants with water is sometimes necessary to assist binding sites in catalytic reactions, thereby achieving desirable performance. Here, we report the design of a CeSnBeta catalyst featuring dual Lewis acidic sites for the efficient production of isobutene from acetone via C-C coupling followed by deoxygenation. By incorporating Ce species onto SnBeta, which was synthesized through liquid-phase grafting of dealuminated Beta, we created confined dual Lewis acidic centers within Beta zeolites. The cooperative action of Ce species and framework Sn sites within this confined environment enabled selective catalysis of the acetone-to-isobutene cascade reactions, showcasing enhanced stability even without the presence of water.

Production of Renewable Hydrocarbon Biofuels with Lignocellulose and Its Derivatives over Heterogeneous Catalysts.

In recent years, the issues of global warming and CO2 emission reduction have garnered increasing global attention. In the 21st Conference of the Parties (convened in Paris in 2015), 179 nations and the European Union signed a pivotal agreement to limit the global temperature increase of this century to well below 2 K above preindustrial levels. To fulfill this objective, extensive research has been conducted to use renewable energy sources as potential replacements for traditional fossil fuels. Among them, the production of hydrocarbon transportation fuels from CO2-neutral and renewable biomass has proven to be a particularly promising solution due to its compatibility with existing infrastructure. This review systematically summarizes research progress in the synthesis of liquid hydrocarbon biofuels from lignocellulose during the past two decades. Based on the chemical structure (including n-paraffins, iso-paraffins, aromatics, and cycloalkanes) of hydrocarbon transportation fuels, the synthesis pathways of these biofuels are discussed in four separate sections. Furthermore, this review proposes three guiding principles for the design of practical hydrocarbon biofuels, providing insights into future directions for the development of viable biomass-derived liquid fuels.

Efficient hydrodeoxygenation of methyl levulinate into pentanoic biofuels over Ru/USY catalysts.

Catalytic hydrodeoxygenation of neat methyl levulinate into pentanoic biofuels is one of the pivotal reactions in biomass valorization. A combined pentanoic acid/methyl pentanoate yield of 92% can be achieved for Ru/USY with a Si/Al ratio of 15 at 220 °C and 40 bar H2. The superior performance of Ru/USY-15 for the efficient production of pentanoic biofuels is attributed to the optimal site balance between the Ru species and strong acid sites (ca. 1 : 5).

Chemocatalytic Conversion of Cellulosic Biomass to Methyl Glycolate, Ethylene Glycol, and Ethanol.

Production of chemicals and fuels from renewable cellulosic biomass is important for the creation of a sustainable society, and it critically relies on the development of new and efficient transformation routes starting from cellulose. Here, a chemocatalytic conversion route from cellulosic biomass to methyl glycolate (MG), ethylene glycol (EG), and ethanol (EtOH) is reported. By using a tungsten-based catalyst, cellulose is converted into MG with a yield as high as 57.7 C % in a one-pot reaction in methanol at 240 °C and 1 MPa O2 , and the obtained MG can be easily separated by distillation. Afterwards, it can be nearly quantitatively converted to EG at 200 °C and to EtOH at 280 °C with a selectivity of 50 % through hydrogenation over a Cu/SiO2 catalyst. By this approach, the fine chemical MG, the bulk chemical EG, and the fuel additive EtOH can all be efficiently produced from renewable cellulosic materials, thus providing a new pathway towards mitigating the dependence on fossil resources.

Catalytic conversion of cellulosic biomass to ethylene glycol: Effects of inorganic impurities in biomass.

The effects of typical inorganic impurities on the catalytic conversion of cellulose to ethylene glycol (EG) were investigated, and the mechanism of catalyst deactivation by certain impurities were clarified. It was found that most impurities did not affect the EG yield, but some non-neutral impurities or Ca and Fe ions greatly decreased the EG yield. Conditional experiments and catalyst characterization showed that some impurities changed the pH of the reaction solution and affected the cellulose hydrolysis rate; Ca and Fe cations reacted with tungstate ions and suppressed the retro-aldol condensation. To obtain a high EG yield, the pH of the reaction solution and the concentration of tungstate ions should be respectively adjusted to 5.0-6.0 and higher than 187ppm. For raw biomass conversion, negative effects were eliminated by suitable pretreatments, and high EG yields comparable to those from pure cellulose were obtained.

Catalytic conversion of cellulose to ethylene glycol over a low-cost binary catalyst of Raney Ni and tungstic acid.

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+H(2 WO(4) ). 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: H(4)SiW(12)O(40)

Hydrolysis of cellulose into glucose over carbons sulfonated at elevated temperatures.

The hydrolysis of cellulose over sulfonated carbons was promoted greatly by elevating the sulfonation temperature. With 250 degrees C-sulfonated CMK-3 as a catalyst, the cellulose was selectively hydrolyzed into glucose with the glucose yield as high as 74.5%, which is the highest level reported so far on solid acid catalysts.