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Physical properties of AlP1.1Zrx-T catalysts.
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Guaiacol produced by O-methylation of catechol with methanol over solid catalysts is a green environmental synthesis route. In order to achieve high catalytic efficiency, it is quite necessary to employ low-cost catalysts with high activity and stability. Herein, series of aluminophosphate catalysts were synthesized by a simple precipitation route...
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... It is well-known that guaiacol is a vital chemical feedstock and intermediate for the production of flavorings, fragrance, pharmaceuticals and a variety of other specialty chemicals [1][2][3][4]. Traditionally, the O-methylation of catechol with toxic alkylating agents (methyl halide, methanol, phosgene or dimethyl sulfate) using a stoichiometric amount of strong base is usually adopted for the industrial production of guaiacol, but this method produces large amounts of hypersaline organic wastewater and the stoichiometric consumption of NaOH [4][5][6]. Dimethyl carbonate (DMC), a green methylating reagent, is considered as a nontoxic, efficient, and environmentally acceptable alternative to toxic methylation reagents [7][8][9][10]. ...
The O-methylation of catechol is an effective method for the industrial production of guaiacol used as an important chemical. However, the low catechol conversion and poor catalyst stability are the most critical issues that need to be addressed. Herein, the O-methylation of catechol with dimethyl carbonate was investigated over aluminophosphate (APO) catalysts, using a continuous-flow system to produce guaiacol. APO catalysts were synthesized with varying P/Al molar ratios and calcination temperatures to study their effects on catalytic performance for the reaction. The physico-chemical properties of the APO catalysts were thoroughly investigated using XRD, NH3-TPD, CO2-TPD, FTIR, and Py-FTIR. The P/Al molar ratio and catalyst calcination temperature significantly influenced the structure and texture, as well as the surface acid-base properties of APO. Both the medium acid and medium base sites were observed over APO catalysts, and the Lewis acid sites acted as the main active sites. The APO (P/Al = 0.7) exhibited the highest catalytic activity and excellent stability, due to the suitable medium acid-base pairs.
The acetalization of furfural and ethanol was investigated over aluminophosphate (APAl) catalysts using both batch and flow reaction systems to produce furfural diethyl acetal (FDA). APAl catalysts were synthesized with varying P/Al ratios and calcination temperatures to study their effects on Brønsted acid active sites for the reaction. Catalysts were characterized by N2 adsorption and Pyridine (PY) and 2,6-dimethylpyridine (DMPY) pulse chromatography titration. A maximum of 89 % furfural conversion and >99 % selectivity of FDA was obtained for the best catalyst (APAl-85/15-A-773) under batch conditions within 30 min at room temperature. On the other hand, the flow system provided a maximum of 92 % furfural conversion. APAl-85/15-A-773 catalyst was also reusable, highly stable, and exhibited a high catalytic performance for furfural acetalization with ethanol at room temperature.