Study New Catalysts Applied In Alkylation Of Toluene With Tert-Butanol

In this paper, three type of activated bentonite from east China, central China and north China had been studied on alkylation of toluene with tert-butanol. Catalytic test experiment indicated that Lin-an activated bentonite had the most obvious effect for alkylation, followed by E-zhou activated bentonite, then Yi-xian activated bentonite. Three activated bentonites were characterized using the BET and pyridine adsorption infrared spectroscopy (FT-IR) measurements to investigate their physical and chemical properties, acid strength and acidity. The FT-IR result showed that Lin-an activated bentonite with higher ratio of L acid and B acid had good catalytic activity and selectivity. Using Lin-an bentonite as catalyst, the optimum toluene conversion and p-tert-butyltoluene were obtained when the catalyst calcined temperature was 150℃, the molar ratio of toluene and tert-butanol was 2, the reaction temperature was 180℃, the reaction pressure was 0.4MPa, space velocity was 4h-1. Through studying the regenerative results, the Lin-an bentonite could be regenerated, but catalyst activity decreased because of a large amount of acid lost. Choosing Lin-an bentonite as the carrier, load Rare Earth, Lewis acid and oxides to modify their character and synthesize a series of supported catalyst. It was found that cerium carbonate modified catalyst could decrease toluene conversion, but remain a high p-tert-butyltoluene selectivity. The calcinated temperature will increase the toluene conversion, reduce the p-tert-butyltoluene selectivity. Adding ZnCl2 could significantly improve selectivity, but fail to increase catalytic activity. The ZnCl2 loading and calcination temperature both were important factors for alkylation. The higher load was beneficial to p-tert-butyltoluene selectivity. With increasing the calcination temperature, the conversion rate had fallen, and the selectivity first increased and then decreased. BET, XRD, TG-DTG, FTIR characterization methods were used to investigate ZnCl2 modified catalyst. The results showed that specific surface area and average pore size had declined after modified, and Lewis acid had been greatly improved. Catalytic test experiment indicated that the catalytic activity and selectivity could be correlated with the acid properties and the proportion of the acid site. Lewis acid was beneficial to selectivity and inhibiting the side reaction of toluene to reduce toluene conversion.