Capillary microreactor with a catalytic coating based on mesoporous titanium dioxide for the selective hydrogenation of 2-methyl-3-butyn-2-ol

Abstract

A continuously working capillary microreactor with a catalytic coating based on mesoporous titanium dioxide with embedded Pd nanoparticles was tested in a reaction of the selective hydrogenation of 2-methyl-3-butyn-2-ol (MBI). The catalytic coatings were obtained by the supporting of a carrier sol, which contained colloidal Pd nanoparticles, onto the internal wall of a quartz capillary with a diameter of 250 μm in the dynamic mode. The effects of the concentration of MBI in methanol (0.05–0.2 mol/L), the partial pressure of hydrogen (0.28–1.0 atm), and the reaction temperature (308–333 K) on the catalyst activity and the selectivity of reaction were studied. High selectivity for the formation of the semi-hydrogenated product 2-methyl-3-buten-2-ol was reached at 313 K in an atmosphere of pure hydrogen. At a conversion of 99.9%, the selectivity was 92.3%, which is 15.5% higher than that in a batch reactor. The rate of hydrogenation on the Pd/TiO₂ coating was higher by one order of magnitude than that on a commercial Lindlar catalyst. The coating remained stable upon the continuous passage of the flow of a reaction mixture for 500 h.