Microkinetic Analysis of the Methane Steam Reforming on a Ru-Supported Catalytic Wall Reactor

Green, efficient, and economic energy conversion from methane steam reforming requires understanding the reaction mechanism and intensification of reactor design to better convert energy at plant scale. On this research, a Ru catalytic wall reactor was prepared to conduct kinetic measurements of the methane steam reforming at low temperatures from 573 to 723 K, and then a microkinetic framework including a basic reforming mechanism and computational load saving methods was developed. The products were hydrogen and carbon dioxide, and the conversion of methane was promoted in high steam/carbon ratio (S/C) and low pressure region. Microkinetic simulation revealed that the methane decomposition and activated water decomposition path were the main reaction pathways, OH*, CO*, H*, and O* were the main intermediates, and small amount of intermediates on the catalyst surface during the reaction may promote methane reforming in the high S/C and low pressure region. It was found that the overall reforming was controlled equivalently by kinetic and thermodynamic mechanisms, according to the calculated contribution of steps and intermediates on reaction progress

Hydrothermal Extraction of Antioxidant Compounds from Green Coffee Beans and Decomposition Kinetics of 3‑<i>o</i>‑Caffeoylquinic Acid

Separation of antioxidant compounds (caffeoylquinic acids (CQAs), phenolics, melanoidin, and caffeine) from green coffee beans with hydrothermal extraction and decomposition kinetics of 3-<i>o</i>-caffeoylquinic acid (3-CQA) are reported. Antioxidant capacity (AOC) of the extracts increased as extraction temperature was increased up to 410 K and then it decreased up to extraction temperatures of 500 K. As extraction temperature was further increased above 500 K, AOC remarkably increased. The decomposition rate of 3-CQA in water was determined from 433 to 513 K. The increase and decrease in AOC with extraction temperature can be attributed to the hydrolysis of oligomeric structures (glycosides) in the coffee beans that yield CQAs, the decomposition of the CQAs, and to the formation of melanoidins that had a characteristic brown color. Hydrothermal extraction provides an effective method for the separation of antioxidant compounds from green coffee beans, and the effluent extracts may be suitable for food products