Computer generation of detailed reaction networks in hydrocracking of Fischer-Tropsch wax

Abstract

Fischer-Tropsch synthesis (FTS) wax is a mixture of linear hydrocarbons with carbon number from C7 to C70+. Converting FTS wax into high-quality diesel (no sulfur and nitrogen contents) by hydrocracking technology is attractive in economy and practicability. Kinetic study of the hydrocracking of FTS wax in elementary step level is very challenging because of the huge amounts of reactions and species involved. Generation of reaction networks for hydrocracking of FTS wax in which the chain length goes up to C70 is described on the basis of Boolean adjacency matrixes. Each of the species (including paraffins, olefins and carbenium ions) involved in the elementary steps is represented digitally by using a ( N + 3) × N matrix, in which a group of standardized numbering rules are designed to guarantee the unique identity of the species. Subsequently, the elementary steps are expressed by computer-aided matrix transformations in terms of proposed reaction rules. Dynamic memory allocation is used in species storage and a characteristic vector with nine elements is designed to store the key information of a ( N + 3) × N matrix, which obviously reduces computer memory consumption and improves computing efficiency. The detailed reaction networks of FTS wax hydrocracking can be generated smoothly and accurately by the current method. The work is the basis of advanced elementary-step-level kinetic modeling.