Currently, Euro 5 (no more than 10 ppm sulfur content) and Euro 6 (less than 10 ppm sulfur content) diesel motor fuels are produced worldwide. High-quality diesel fuels are produced by removing sulfur compounds using a hydrodesulfurization process. This article is devoted to the study of hydrodesulfurization of diesel fuel containing 120 ppm of sulfur compounds in the presence of an Al-Ni-Mo-O catalyst with a 98% diesel fuel purification rate. According to the Langmuir–Hinshelwood–Panchenkov theory, a kinetic model of the process is developed with the calculation of the theoretical change in the entropy and enthalpy of the activation of the hydrodesulfurization process. The mathematical model, for the first time, takes into account the influence of the pressure of substances involved in the process on the transformation of sulfur-containing compounds. A mechanism for diesel fuel hydrotreating from sulfur-containing compounds is formulated using a generalized quantum-chemical principle. The hydrodesulfurization mechanism includes nine stages. The formulated mechanism and developed mathematical model of hydrotreating fully describe the reaction of the hydrodesulfurization of diesel fuel and show the possibility of regulating and controlling this industrially important process.
Novel bimetallic Pd-Mn/Al2O3 catalysts are designed by the decomposition of cyclopentadienylmanganese tricarbonyl (cymantrene) on reduced Pd/Al2O3 in an H2 atmosphere. The peculiarities of cymantrene decomposition on palladium and, thus, the formation of bimetallic Pd-Mn catalysts are studied. The catalysts are characterized by N2 adsorption, H2 pulse chemisorption, temperature-programmed desorption of hydrogen (TPD-H2), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The modified catalysts show the changed hydrogen chemisorption properties and the absence of weakly bonded hydrogen. Using an organomanganese precursor provides an uniform Mn distribution on the catalyst surface. Tested in hydrogenation of acetylene, the catalysts show both higher activity and selectivity to ethylene (20% higher) compared to the non-modified Pd/Al2O3 catalyst. The influence of the addition of Mn and temperature treatment on catalyst performance is studied. The optimal Mn content and treatment temperature are found. It is established that modification with Mn changes the route of acetylene hydrogenation from a consecutive scheme for Pd/Al2O3 to parallel one for the Pd-Mn samples. The reaction rate shows zero overall order by reagents for all tested catalysts.