Modeling and optimizing of steam pyrolysis of dimethyl formamide by using response surface methodology coupled with Box-Behnken design

Abstract

A non-catalytic steam pyrolysis of N,N-dimethyl formamide (DMF) was studied in a SS 316 plug flow reactor at atmospheric pressure as a waste solvent minimization method. The reaction products were analyzed by using gas chromatography-thermal conductivity detector and high performance liquid chromatography-refractive index detector. The optimization of process variables namely, temperature, flow rate and water to DMF ratio (v/v) for the maximum conversion of DMF have been studied by response surface methodology (RSM) coupled with a Box-Behnken design. The analysis of variance (ANOVA) data shows the conversion of DMF significantly enhances with temperature. Higher flow rate has adverse effect on DMF conversion, whereas water to DMF ratio (v/v) shows negligible effect on conversion of DMF. With the help of a developed RSM model, the highest conversion of DMF (89.82wt%) was predicted at 1100°C, 0.48ml/min and water:DMF ratio of 1.35 (v/v). Based on the experimental design, eight empirical models were developed those depict the interacting effect of different sets of operating variables on conversion of DMF and yield of seven products. Effect of process variables on yield of CO2 and N2 were studied, individually. Oxidative pyrolysis of DMF was also investigated, which shows significant reduction in the coke formation with increasing H2O2 to DMF mol ratio.