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Ti-containing phosphate(Ti-P-O) catalysts with different molar ratios of P to Ti(0—2.0) were synthesized and characterized by XRD, N_ 2 -adsorption/desorption, IR and temperature-programmed desorption(TPD) methods. The catalytic properties of Ti-P-O samples in the vapor-phase O-methylation of catechol with methanol were also studied. The catechol conversion increases with the increase of the molar ratio of P to Ti in a range of 0—0.33, while a further increase in the P content leads to a decrease of the catalytic activity. Meanwhile, the selectivities of the catalysts to the main product(guaiacol) increase gradually with the increase of the molar ratio of P to Ti. The presence of relatively strong Lewis acidic and/or basic sites in the P-free catalyst should be responsible for the formation of C-alkylation products. The weak acid-base characteristics of the catalysts are favourable for the mono-O-methylation of catechol. In comparison with the Lewis acidic sites, the Brnsted acidic sites on the catalysts are more active for the title reaction.
Ti-containing phosphate (Ti-PO) catalysts with different molar ratios of P to Ti (0-2.0) were synthesized and characterized by XRD, N 2 -adsorption / desorption, IR and temperature- programmed desorption properties of Ti-PO samples in the vapor-phase O-methylation of catechol with methanol were also studied. The catechol conversion increases with the increase of the molar ratio of P to Ti in a range of 0-0.33, while a further increase in the se content of the catalysts to the main product (guaiacol) increase gradually with the increase of the molar ratio of P to Ti. The presence of relatively strong Lewis acidic and / or basic sites in the P-free catalyst should be responsible for the formation of C-alkylation products. The weak acid-base characteristics of the compounds are favourable for the mono-O-methylation of catechol. Brnsted aci dic sites on the catalysts are more active for the title reaction.