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The conversion of n-hexane into its isomers is highly relevant in the petroleum refining industry due to its contribution to improving gasoline quality by increasing the octane number. This study presents a comparative analysis of eight reaction schemes for the C6 series isomerization process. It was demonstrated that incorporating rigorous chemical equilibrium information, based on experimental data, yields virtually identical results across all schemes, enabling a detailed analysis. Five schemes were taken from the literature, two were modified to ensure linear independence, and one was proposed in this study under the same criteria. It was confirmed that using linearly independent schemes reduces the number of reactions without affecting model accuracy, facilitating its numerical solution. Each scheme was evaluated using simulations under industrial conditions with a kinetic model that includes 16 reactions. The results show predictions with average errors of 1.44% in reactor outlet temperature and 3.25% in molar flow rates. The kinetic constants for each reaction of the C6 series were generalized, ensuring their invariability regardless of the scheme used, allowing for their application to different schemes and eliminating the need for individualized tuning of the isomerization reactors in the process under study.

A challenge for the oil refinement industry is the production of high-octane gasoline with a low benzene content. This work reports the calculation of the atmospheric benzene emissions generated from gasoline storage, transfer, and transport operations in Mexico, estimating 1.48 KBPD of environmental release. The aim was to estimate the minimum benzene emissions through operative improvements in refineries, initially by performing simulations of the Naphtha Catalytic Reforming (NCR) process using ASPEN HYSYS® ver. 8.8 (34.0.08909) and then by optimizing the operative conditions to improve the reformate quality while reducing the benzene content. The operative ranges comprised hydrogen/hydrocarbon (H2/HC) feedstock molar ratios from 2.0 to 6.0 and reaction temperatures from 450 to 525 °C, which were used as independent variables to assess the benzene content and the Research Octane Number (RON) of the produced gasoline. The Surface Response Method (SRM) and multi-objective optimization analysis were applied. The improved operative conditions were 491 °C and a H2/HC ratio of 2.0, which allowed us to obtain a RON value of 89.87, an aromatics value of 37.39% (v/v), and a benzene value of 1.48% (v/v), with an estimated 16.44% drop in atmospheric benzene emissions, meaning a reduction in greenhouse gas emissions and climate change, thus favorably impacting public health by improving refinery operations. The simulation outcomes were compared with industrial-scale data and the experimental results, with significant similitudes being observed.

The conversion of n-hexane into its isomers is highly relevant in the petroleum refining industry due to its contribution to improving gasoline quality by increasing the octane number. This study presents a comparative analysis of eight reaction schemes for the C[sub.6] series isomerization process. It was demonstrated that incorporating rigorous chemical equilibrium information, based on experimental data, yields virtually identical results across all schemes, enabling a detailed analysis. Five schemes were taken from the literature, two were modified to ensure linear independence, and one was proposed in this study under the same criteria. It was confirmed that using linearly independent schemes reduces the number of reactions without affecting model accuracy, facilitating its numerical solution. Each scheme was evaluated using simulations under industrial conditions with a kinetic model that includes 16 reactions. The results show predictions with average errors of 1.44% in reactor outlet temperature and 3.25% in molar flow rates. The kinetic constants for each reaction of the C6 series were generalized, ensuring their invariability regardless of the scheme used, allowing for their application to different schemes and eliminating the need for individualized tuning of the isomerization reactors in the process under study.