چكيده به لاتين
In this research, with the aim of controlling textural properties of HDS catalyst support, pseudoboehmite is synthesized through one-pot, solvent-deficient method which is the reaction of micro bubbled CO2 gas with NaAlO2 aqueous solution. Considering novelty of the synthesized through, to fill the knowledge gap, comprehensive study of preparation parameters effects on pseudoboehmite properties was performed. The effects of eight parameters were studied and effectiveness of each parameter was investigated. One of the most important outputs of the performed Placket-Burman screening design is the ability to control properties of the prepared pseudoboehmite and achieving the maximum BET surface area, average pore size and pore volume of 365 m2/g, 155 Å and 1.08 cm3/ g respectively.
In order to obtain suitable zeolite for the USY/γ-Al2O3 composite support, the steaming process was selected and studied. Comprehensive experiments were conducted to fill the knowledge gap in prioritizing the parameters of the NaY zeolite thermo-chemical processing, which are effective on the acidic and superficial properties of USY zeolite. The maximum values for Si to Al molar ratio, acidity, BET surface area, average pore size and pore volume were found to be 11.75±1.19, 4.17±0.47 mmole NH3/g, 739±17 m2/g, 20.7±0.9 Å and 0.351±0.008 cm3/g, respectively. Using developed models, the ability to control textural and acidity properties of pseudoboehmite and zeolite was provided.
Effects of the catalyst average pore size (DPave) on its activity in HDS of the cracked (VisGO) and straight run gasoil (AGO) blend were investigated. Seven γ-Al2O3 catalyst support and NiMo catalyst were prepared to have adsorbed (and desorption) DPave BJH in range of 6.3 (5.2) to 21.5 (18.6) nm and 5.0 (3.7) to 20.3 (17.2) nm. The highest sulfur removal from AGO and 5 wt% mixture of VisGo in AGO were obtained using catalysts with DPave of 8.0 (5.9) and 9.1 (7.2) nm. The proposed synthesis route would be an efficient alternative method to prepare mesoporous γ-Al2O3 supports with precisely controlled average pore size in a wide range of a few up to 20 nanometers.
Direct and interactive effects of USY/γ-Al2O3 support composition, total metal loading (Ni+Mo), molar ratios of Ni/(Ni+Mo) and EDTA/Ni on textural properties, sulfide catalyst sulfur content and catalyst activity in HDS of AGO and VisGO blend were investigated through preparation of 27 catalysts. Surface area, pore volume and BJH adsorption (desorption) average pore sizes of the synthesized catalysts were in the range of 199 to 277 m2/g, 0.50 to 0.63 cm3/g and 88 to 107 Å, respectively. The amount of sulfur remained in the processed hydrocarbons using different catalysts were measured and are in the range of 10 to 37 ppm. Based on the RSM model, it is possible to achieve very low sulfur content (2.3 ppm) using the optimal catalyst. The optimum sample is approved hydrodesulfurization to 1.3 ppm.
