Effect of Phosphoric Acid on HZSM-5 Catalysts for Prins Condensation to Isoprene from Isobutylene and Formaldehyde
- 4 Downloads
A series of HZSM-5 zeolites modified with different amounts of phosphoric acid(P/HZSM-5) was pre-pared. The physicochemical features of the P/HZSM-5 catalysts were characterized via X-ray diffraction(XRD), N2 adsorption-desorption, NH3-temperature programmed desorption(NH3-TPD) and Fourier tranform infrared(FTIR) spectra of the adsorbed pyridine, and the performances of the catalysts for Prins condensation to isoprene from iso-butylene and formaldehyde were investigated. The maximum isobutene conversion and isoprene selectivity were 10.3% and 94.6% on the HZSM-5 catalyst with a Si/Al molar ratio of 600 using 5%(mass fraction) phosphoric acid. The phosphoric acid modification not only modulated the amount of acidic sites but also regulated the acid type. An appropriate amount of weak Lewis and Brönsted acid sites served as the active sites for the condensation of isobutene with formaldehyde, and the strong acid sites could cause side reactions and coke deposition.
KeywordsIsobutylene Isoprene Formaldehyde HZSM-5 catalyst Phosphoric acid modification
Unable to display preview. Download preview PDF.
- Hamamoto Y., Mitsutani A., Method of Producing Conjugated Diole-fins, US23230062A, 1965Google Scholar
- Mitsntani A., Process for the Manufacture of Isoprene and Isobutene, US43573165A, 1966Google Scholar
- Dang Z., Ding S., J. Mol. Catal., 1987, 3(1), 146Google Scholar
- Dumitriu E., Gongescu D., Hulea V., Heterogeneous Catalysis and Fine Chemicals III 1993, 78, 669Google Scholar
- Zhang R. Z., Wen S. B., Xing P., Chem. J. Chinese Universities, 2017, 38(1), 126Google Scholar