Efficient soluble and polymer cross linked insoluble poly-4-vinyl pyridine metal(V) chloride catalysts for esterification of butanol with acetic acid

Abstract

New soluble and insoluble Ta, Mo and Sb pentachloride complex catalysts have been prepared using pyridine and polymer supported cross-linked (poly-4-vinyl pyridine) beads (PSCPVP), respectively. The prepared catalysts are characterized with FTIR, SEM, EDAX, CHN and TGA. The catalytic activities of these catalysts have been examined for esterification of acetic acid with butanol through gas chromatographic technique. The soluble complex catalyst show better activity than the insoluble catalyst, but it suffers from recovery and recyclability. The insoluble catalysts maintain stability up to three recycle times. From the k_obs values, it is found that all the soluble catalysts of Py-MCl₅, M=Ta, Mo & Sb (k_obs=7.26, 5.48 & 1.47×10³ min^-1) showed higher catalytic activity than the insoluble PSCPVP-MCl₅ (k_obs=5.18, 2.24 & 0.87 x10³ min^-1)_, but the latter catalysts are superior to the former in terms of recyclability. The catalytic activity of soluble Py-TaCl₅, Py-MoCl₅, Py-SbCl₅ catalyst is found to be 1.40, 2.44 and 1.68 times higher than PSCPVP-TaCl₅, PSCPVP-MoCl₅ and PSCPVP-SbCl₅, respectively. PSCPVP-TaCl₅ catalyst is found to be the superior most catalyst among the three catalysts. Further, these catalysts can be used in column batch reactors to conduct the reaction in continuous mode.