Changle Jiang

Microwave-assisted acid activation creates an early kinetic window for preferential REE release relative to Fe, while thermomorphic [Hbet][Tf ₂ N] facilitates subsequent phase partitioning.

Catalytic gasification of biomass is a promising method for producing hydrogen-rich syngas, which is a valuable resource for clean-energy applications. In this study, microwave-assisted biomass gasification was compared with conventional thermally driven biomass gasification using pinewood as the biomass without the use of external gasifying agents (such as air, steam, and CO₂), under non-catalytic and catalytic conditions. The catalysts consisted of either an iron or a nickel catalyst, and the pinewood used as biomass contained 42% oxygen. This comparative analysis explores the differences in reaction chemistry, product yields, and the role of key reactions such as the water gas shift (WGS) reaction, Boudouard reaction, etc. The gas-phase and liquid-phase products were analyzed using online gas chromatography, and the fresh and spent catalysts were analyzed using X-ray diffraction (XRD) techniques. It was found that microwave-assisted gasification offers advantages in terms of enhanced reaction efficiency, catalyst stability, and hydrogen yield. For the microwave-assisted reaction, the gas yield reached 87%, the char yield was 12.1%, and the tar yield was less than 1% (0.793%) at 550 °C. In contrast, thermal-assisted gasification using the same catalyst produced a gas yield of 85.796%, char yield of 11.438%, and higher tar yield of 2.8% at 900 °C. The higher microwave-assisted performance was attributed to faster heating and better control over reaction conditions, higher reaction rates, and more favorable conditions for hydrogen production.

Recent advancements in microwave-driven nonoxidative catalytic synthesis of C₂H₄ from CH₄ coupling offer a promising, energy-efficient, and eco-friendly alternative to conventional methods, where selective heating under microwave irradiation enables comparable conversions at substantially lower bulk temperatures and shorter reaction times. This study explores the performance of an MnO_X-based catalyst supported on CeO₂ and HY zeolite (silica-to-alumina ratio = 5.1) for the nonoxidative coupling of CH₄ (NOCM) under microwave irradiation. Inspired by the well-established efficacy of MnO_X catalyst in oxidative CH₄ coupling (OCM), their application in NOCM has also shown significant performance. The catalytic system achieved 15% CH₄ conversion and 99% selectivity toward C₂ hydrocarbons and maintained 64% selectivity toward C₂H₄ surpassing the yields reported in the literature even at higher temperatures (700-1000 °C). Catalyst performance was correlated with measurements by in situ Raman spectroscopy, and additional characterizations were performed using H₂-temperature programmed reduction , NH₃-temperature programmed desorption, and BET surface area analysis to understand structural changes during the reactions. These findings suggested that Mn functions as active sites for CH₄ activation in nonoxidative environments while also promoting efficient C-C coupling under microwave irradiation.

Modern technologies transform biomass into commodity chemicals, biofuels, and solid charcoal, making it appear as a renewable resource rather than organic waste. The effectiveness of Mo, Fe, Co, and Ni metal catalysts was investigated during the gasification of lignocellulosic pinewood. The primary goal was to compare the performance of iron and nickel catalysts in the low- and high-pressure production of syngas from pinewood. This is the first study that has reported high-pressure gasification of pinewood without the use of an external gasifying agent, producing syngas containing hydrogen, carbon monoxide, and carbon dioxide along with considerable amounts of methane with or without a catalyst. Also, the same gasification at low pressures was compared. In this study, the iron catalyst produces syngas more efficiently at higher pressure and 800 °C, and contains 43 mol % H₂, 22 mol % CO₂, 26 mol % CH₄, and 8 mol % CO in comparison to the nickel catalyst. High pressure produces a large amount of methane too. The nickel catalyst produces higher syngas at low pressure and 850 °C, and contains 55 mol % H₂, 9 mol % CO₂, 5 mol % CH₄, and 30 mol % CO. Low-pressure gasification produces less amounts of CH₄ and CO₂. Also, the H₂/CO ratio is ∼1.81 using the nickel catalyst at low pressures, which is good for utilizing syngas as a feedstock. These results highlight the importance of catalyst selection, reactor configuration, and operating circumstances in adjusting gasification product composition. The study’s findings provide information about optimizing syngas production from pinewood, which is critical for the development of sustainable and efficient energy conversion technologies.