No abstract

Dewaxing by isomerization is widely used to produce winter and arctic grades of diesel fuel. Preliminary feed hydrotreatment and pure hydrogen are usually used in order to avoid poisoning of the catalyst by sulfur and nitrogen. However, combining hydrotreatment and dewaxing in one reactor has some advantages, such as lower capital and operating costs. In such a configuration, a dewaxing catalyst works in sour environments, defined by sulfur and nitrogen presented in the feed stream. In the presented work, Pt-containing catalysts based on commercial zeolites with one-dimensional channels and their mixtures (ZSM-23, ZSM-22, ZSM-12, EU-2, SAPO-11, ZSM-23+ZSM-12, and ZSM-23+EU-2) were prepared, characterized using different analytical techniques (X-ray diffraction, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy, N2 sorption, and infrared spectroscopy), and tested in dewaxing of the diesel fraction under sour conditions. It was found that catalyst activity, dewaxed product yield, and quality indicators (aromatic hydrocarbon content and density) were highly sensitive to zeolite channel size, while catalyst acidity and zeolite crystal size were less important factors. The highest activity was shown by catalysts based on EU-2 and ZSM-12, which had the widest channels. The highest product yield was observed for the catalyst based on EU-2, which had a medium channel size among compared zeolites. Wider zeolite channels promoted the metal function of catalysts that led to a decrease in the aromatic hydrocarbon content of dewaxed products. Using the mixtures of ZSM-23+ZSM-12 and ZSM-23+EU-2 did not lead to visible synergetic effects. Using different binder materials (Al2O3, TiO2, and ZrO2) did not significantly affect the quality or yield of dewaxed products.

Dewaxing by isomerization is one of the most important processes for base oil production of groups II and III. The core of this process is the isomerization of n-paraffins of the feed. While individual paraffin isomerization using different catalysts is thoroughly investigated in many research studies, the effect of zeolites and process conditions on dewaxing by isomerization of different real hydrocarbon feeds is less well known. In the presented work, ZSM-23 and SAPO-11 zeolite-based catalysts were prepared, characterized using different analytical techniques (X-ray diffraction, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy, N2-sorption, and NH3-TPD), and tested using dewaxing by isomerization of hydrocracked oil and petroleum wax under conditions close to those used in industry. Differences in quality parameters of dewaxed products obtained using different catalysts were also investigated. It was found that the ZSM-23-based catalyst was more active than the catalyst prepared using SAPO-11. While in dewaxing of hydrocracked oil both investigated catalysts showed similar product yields, in petroleum wax isomerization, a SAPO-11-based catalyst was more selective and showed greater yields of high-VI products. It was also established that using the SAPO-11-based catalyst led to dewaxed products with lower density, viscosity, and saturated hydrocarbon content compared with those obtained on the ZSM-23-based catalyst. Findings of this work can help researchers to develop more effective dewaxing catalysts for different hydrocarbon feeds.

No abstract

No abstract