Kinetic modeling of liquid phase catalytic alkylation of guaiacol with cyclohexene

MONTAÑEZ-VALENCIA, MARDELLY KATERYNE; PADRÓ, CRISTINA LILIANA; SAD, MARÍA EUGENIA; BERTERO, NICOLÁS MAXIMILIANO

Chemical Engineering Journal Advances

Elsevier

Año: 2021

2666-8211

The kinetics of the liquid-phase alkylation ofguaiacol (G) with cyclohexene (CH) over Amberlyst 36 resin was studied usingLangmuir-Hinshelwood-Hougen-Watson (LHHW) heterogeneous kinetic models.Catalytic tests were performed in a batch reactor, in solvent-less conditions,at 363 K, 1 bar, 600 RPM, using a G:CH molar ratio equal to 5 with a totalvolume of 30 ml and 0.5 g of solid catalyst. The alkylation of G with CH formedcyclohexyl-2-methoxyphenylether (CHMPE) by O-alkylation andcyclohexyl-2-methoxyphenol isomers (CHMP) by C-alkylation. Furthermore, CHMPEisomerizated into CHMP. A negligible amount of cyclohexylcyclohexene (CHC) wasobserved by dimerization of CH. Among these products, CHMP are importantintermediaries for the production of resins, antioxidants, drugs, polymericadditives, agrochemicals, etc.Several LHHW kinetic models, varying the rate limitingstep of reactions, were proposed in order to elucidate a reaction mechanism. Thefitting of experimental data was performed consecutively by: (1) a stochasticoptimization method and (2) by nonlinear regression, using theLevenberg?Marquardt algorithm, reducing the probability of reaching localminima in the objective function. The selected kinetic model considersthat: (a) the rate limiting step for both the O-alkylation and C-alkylation isthe surface chemical reaction between adsorbed G and adsorbed CH; (b) theadsorption of the O-alkylated products is the rate limiting step for theisomerization into C-alkylated products. Finally, this kinetic model that fits experimental data appreciably well from both physicaland statistical point of view, suggest that CH adsorbs stronger than G overAmberlyst 36 catalyst.