Influence of flowrate and composition of the alkanes dehydrogenation process feedstock on by-products concentration in the linear alkylbenzene sulfonic acid manufacturing technology

Synthesis of surfactants based on linear alkylbenzenesulfonates is a complex multi-stage process that includes the following stages: alkanes dehydrogenation on Pt-containing catalyst, dienes hydrogenation on Ni-containing catalyst, HF-catalyzed alkylation of benzene with alkenes, and sulfonation of linear alkylbenzenes (LAB) with sulfur trioxide in a film reactor yielding alkylbenzene sulfonic acid (ABSA). When developing mathematical models of multi-stage processes it is necessary to consider the contingency of the apparatuses in the chemical-technological system. The design of the sulfonation reactor, as well as the feedstock composition and the dehydrogenation unit performance, i.e., the LAB flowrate to sulforator, significantly affects the ABSA synthesis efficiency. The studies were performed using the unsteady mathematical models of conjugated dehydrogenation and sulfonation processes. As a result, we determined the optimal design of the sulfonation reactor with number of tubes n = 40 and diameter d = 43 mm. We also outlined the preferred method for increasing the ABSA yield by switching to a double-reactor alkane dehydrogenation scheme with a flowrate of 100 m³/h for two dehydrogenation reactors. This increases yield of alkenes and LAB by 71 %wt.