Phosphotungstic acid

About: Phosphotungstic acid is a research topic. Over the lifetime, 1925 publications have been published within this topic receiving 38059 citations. The topic is also known as: Phosphowolframic acid.

Efficient and controllable ultrasound-assisted depolymerization of organosolv lignin catalyzed to liquid fuels by MCM-41 supported phosphotungstic acid

Abstract: In this study, effects of catalyst types, reaction temperatures, reaction times, reaction solvents and ultrasound frequencies were carefully investigated to improve the yields and characteristics of various depolymerization products of organosolv lignin. Generally, both catalyst types and ultrasound frequencies played important roles in promoting lignin depolymerization and reducing char yield. In particular, the yield and distribution of phenolic monomer (PM) products were greatly influenced by pore structure and acidity of the catalyst. The optimal reaction condition was got in isopropanol at 310 °C for 6 h with 30% ultrasound frequency and 50% phosphotungstic acid (PTA)/MCM-41 catalyst. The highest yields of PM, bio-oil, liquid fuels and lignin conversion were reached as 8.63 wt%, 86.89 wt%, 95.52 wt% and 98.54 wt%, respectively. The results showed that ultrasound acoustic cavitation could enhance the depolymerization of lignin, thus greatly enhancing production of liquid fuels. Simultaneously, the hydrogen composition and high heating value of various lignin depolymerization products improved, and the oxygen content decreased, indicating that hydrogenation and/or hydrodeoxygenation happened during the depolymerization process. Finally, we also found that the 50% PTA/MCM-41 catalyst had high stability; it could be reused for up to five cycles without loss of catalytic activity.

Condensation of pentose-derived furan compounds to C15 fuel precursors using supported phosphotungstic acid catalysts: Strategy for designing heterogeneous acid catalysts based on the acid strength and pore structures

Abstract: The selective condensation of 2-methylfuran and furfural to C15 compounds is performed using supported phosphotungstic acid catalysts in a continuous-flow fixed-bed reactor. The formation of unwanted viscous tetramers (C20) is suppressed when the continuous-flow reaction system is used. Stronger acids, as measured by pKa, improved the condensation of furans, but the number of acid sites was rather weakly correlated with the catalytic activity. Suppressed catalytic activity in tiny pores smaller than 2.8–6.3 nm was also observed. Based on the observations of the acidity and pore structures, a strategy with which to design optimum catalysts for the condensation of furan compounds is suggested.