Ruixue Yangcheng's research while affiliated with Chongqing University and other places

Small-pore zeolites catalyze the methanol-to-olefins (MTO) reaction via a dual-cycle mechanism, encompassing both olefin- and aromatic-based cycles. Zeolite topology is crucial in determining both the catalytic pathway and the product selectivity of the MTO reaction. Herein, we investigate the mechanistic influence of MCM-35 zeolite on the MTO process. The structural properties of the as-synthesized MCM-35 catalyst, including its confined cages (6.19 Å), were characterized, confirming them as the catalytic centers. Then, the MTO reactions were systematically performed and investigated over a MCM-35 catalyst. Feeding pure methanol to the reactor yielded minimal MTO activity despite the formation of some aromatic species within the zeolite. The results suggest that the aromatic-based cycle is entirely suppressed in MCM-35, preventing the simultaneous occurrence of the olefin-based cycle. However, cofeeding a small amount of propene in methanol can obviously enhance the methanol conversion under the same studied reaction conditions. Thus, the exclusive operation of the olefin-based cycle in the MTO reaction, independent of the aromatic-based cycle, was demonstrated in MCM-35 zeolite.

Hydrodeoxygenation (HDO) of lignin derivatives at room‐temperature (RT) is still of challenge due to the lack of satisfactory activity reported in previous literature. Here, it is successfully designed a Pd/UiO‐66‐(COOH) 2 catalyst by using UiO‐66‐(COOH) 2 as the support with uncoordinated carboxyl groups. This catalyst, featuring a moderate Pd loading, exhibited exceptional activity in RT HDO of vanillin (VAN, a typical model lignin derivative) to 2‐methoxyl‐4‐methylpheonol (MMP), and >99% VAN conversion with >99% MMP yield is achieved, which is the first metal‐organic framework (MOF)‐based catalyst realizing the goal of RT HDO of lignin derivatives, surpassing previous reports in the literature. Detailed investigations reveal a linear relationship between the amount of uncoordinated carboxyl group and MMP yield. These uncoordinated carboxyl groups accelerate the conversion of intermediate such as vanillyl alcohol (VAL), ultimately leading to a higher yield of MMP over Pd/UiO‐66‐(COOH) 2 catalyst. Furthermore, Pd/UiO‐66‐(COOH) 2 catalyst also exhibits exceptional reusability and excellent substrate generality, highlighting its promising potential for further biomass utilization.

A series of Zr-based catalysts were prepared using various commercial and cheap organic acids as the coordination agents, and these as-synthesized samples exhibited superior activities to produce lactic acid (LaA) from carbohydrates. Using humic acid (HA) as a typical coordination agent, LaA yield was up to 76% over the resultant Zr-HA, outperforming the most recent reported works. Deeper studies revealed that Zr-HA possessed both acid sites and base sites, and these dual active sites can simultaneously activate xylose, resulting in high yield production of LaA. Besides, Zr-HA also showed excellent reusability and can be reused at least five times.

A novel catalyst prepared by a facile ‘one-pot’ solvothermal method was developed for the efficient production of lower polyols from glucose solution. Under the optimal reaction conditions, the yield of diols was up to 50.7%, outperforming the recent works reported in the literature (<48%). Deeper investigation results revealed that the modification of MgOy on Pt-WOx could tune the surface acid-base properties, thereby promoting the yield of lower polyols. Combining the experimental and characterization results, a possible reaction mechanism during the conversion of glucose to lower polyols over Pt-WOx-MgOy was proposed.

It is highly desirable but of challenge to develop an efficient process for lactic acid (LaA) production from xylose performed in water. Herein, a novel catalyst prepared via a facile solvent-free coordination route is developed to efficiently produce LaA from xylose in water. The structural properties of the prepared catalyst and the reaction conditions are systematically investigated. The production rate of LaA at 190 °C in water is up to 1.8 h⁻¹, outperforming the most recent reports (below 1.1 h⁻¹). Detailed experimental and characteristic studies reveal that the presence of Lewis acidic sites and basic sites in the catalyst structure can not only lower the energy barrier of xylose conversion but also boost the efficient conversion of the active reaction intermediates into LaA. The findings of this work will provide a new approach for the efficient production of LaA from carbohydrates.

Selective and efficient low-temperature hydrodeoxygenation (HDO) of lignin derivatives in water for the production of valuable biofuel and chemicals is still challenging. Herein, we reported biomass carbon-supported ultrafine Pd nanoparticles as highly active and stable catalysts for low-temperature HDO of vanillin (a typical lignin-derived compound) to 2-methoxy-4-methylphenol (MMP). We found that the abundant carboxyl groups on the resultant catalyst greatly accelerated the conversion of the generated intermediate (vanillyl alcohol, VAL), and then, the synergistic catalysis between carboxyl groups and Pd nanoparticles promoted the efficient production MMP through a free-radical pathway. Other lignin derivatives with different functional groups were also efficiently converted to the corresponding products over the prepared catalyst. This work may provide a new idea for designing a biomass-derived catalyst for efficient transformation of various lignin derivatives to produce value-added biofuels and chemicals.

Efficient low‐temperature hydrodeoxygenation (HDO) of lignin derivatives to produce biofuels and high value‐added chemicals is still of challenge. Here, we have constructed a high active and stable 0.2 wt.% Pd/MS‐HZSM‐5(30) catalyst, and 94.7 % yield of 2‐methoxy‐4‐methylphenol (MMP) can be achieved in HDO of vanillin (VAN, a typical platform molecule of lignin derivatives) under milder reaction conditions (60 °C, 5 h, molar ratio of VAN/Pd=1200, water phase), outperforming the most works reported recently. Detailed experimental and mechanistic studies demonstrated that the superior catalytic performance was due to the rapid hydrogenolysis of generated intermediate (vanillyl alcohol, VAL) to MMP proceeded in an interfacial microenvironmental created by Pd NPs and acidic sites in Pd/MS‐HZSM‐5(30). These new insights will provide potential guidance for the efficient low‐temperature production of biofuels and valuable chemicals from lignin derivatives or raw lignin.

Efficient production of high value-added chemicals and biofuels via low-temperature chemoselective HDO of lignin derivatives in water is still of challenge. Here, we construct a low-cost, active and stable Pd/PCE...