Kinetic Study of Novel Nanoporous PDVB - based Catalysts for the Synthesis of a Bio-based Bisphenol

摘要

Depletion of conventional petroleum derived hydrocarbons has led to a global initiative toward the research and development of polymers and composites derived from renewable resources. Bisguaiacol (4,4'-methylenebis(2-methoxyphenol)), a bio-based bisphenol, can be synthesized via electrophilic aromatic condensation from vanillyl alcohol and guaiacol [1]. Bench scale synthesis of bisguaiacol has been shown to be feasible. We present the kinetic study of this acid catalyzed condensation reaction that was investigated under controlled conditions at various temperatures and reactant molar ratios. The effect of catalytic activity on bisguaiacol synthesis was compared between commercial solid acid catalysts, Amberlyst® 15 hydrogen form and Dowex® DR-2030 hydrogen form, and novel synergistic nano-porous poly-divinylbenzene (PDVB)-based catalysts. Fourier-transform infrared spectroscopy (FT-IR) studies revealed the successful addition of acid groups onto the PDVB matrix. Characterization methods of solid catalysts included surface acidity measurements by potentiometric titration, specific surface area determination by nitrogen adsorption, surface topography by scanning electron microscopy (SEM), thermal stability via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC scan showed no thermal transitions of PDVB-based catalysts up to 150 C, and TGA thermograms indicated that the maximum temperature of degradation is between 400 C and 580 C. Surface area of functionalized PDVB-based catalysts estimated from multi-point BET is within the range of 500 - 700 m2/g with nanopore size within the range of 1.53 - 1.61 nm, estimated from BJH model. The results of this study show that the reaction yields achieved with these novel PDVB-based catalysts are comparable to those obtained with the two commercially available counterparts. Additionally, the enhanced acid strength and controllable polarity, as well as the efficient synthesis method, make these PDVB-based catalysts potential competitive alternatives to conventional heterogeneous catalysts.