Sulfur containing compounds of oil cuts cause air pollution, corrosion of metallic equipments and refinery CATALYSTs poisoning, so using HYDRODESULFURIZATION ((HDS)) CATALYSTs and reducing sulfur content of oil cuts is critical. These CATALYSTs generally contain a uniform monolayer dispersion of VIB group metal oxides such as molybdenum oxide and VIII group metal oxides such as cobalt oxide on a carrier preferably g-alumina. In this work successive dry impregnation of g-alumina by ammonium heptamolybdate and cobalt nitrate solutions was used to prepare (HDS) CATALYST samples and then effect of impregnation solution pH. Mo and Co solution concentration, drying rate and feed flow rate on the HYDRODESULFURIZATION performance was investigated. The samples were evaluated via scanning electron microscopy, porosimetery and reactor tests. The CATALYST sample JDS-C5 shows the ability of reducing sulfur content of the feed from 1200 ppm to less than 1 ppm in the refinery (HDS) unit operation conditions (T=290 °C and P=15 bar).

The effect of two different crystal species of alumina on HYDRODESULFURIZATION activity of the corresponding CoMo CATALYSTs was studied. Cylindrical extruded alumina with two different crystal structures i. e. γ-Al2O3 and δ-Al2O3 was prepared using boehmite and nitric acid as a peptizing agent by calcination at 550 ˚ C and 900 ˚ C, respectively. The Al2O3 support were impregnated with 9 wt. % of Mo and 2 wt. % Co via incipient wetness impregnation method. The CoMo/Al2O3 CATALYSTs were used for HYDRODESULFURIZATION ((HDS)) and hydrodenitrification (HDN) of Iranian straight-run gas oil (ISRGO). The supports and CATALYSTs were characterized by nitrogen adsorption-desorption isotherm, XRD, UV-vis-DRS, TPD, TPR and ICP-OES. The (HDS) activity of CoMo/γ-Al2O3 CATALYST was higher than that of CoMo/δ-Al2O3 and was found to be 95. 74%. This result was due to the formation of larger CoMoO4 and MoO3 crystals in CoMo/δ-Al2O3 CATALYST which reduces the active metal phase dispersion and the performance of the CATALYST. The (HDS) activity of CoMo/γ-Al2O3 CATALYST was remarkable as the metal content of the CATALYST was low. The HDN activity of CoMo/γ-Al2O3 was also about 66%.

A specific type of mesopore extrudates gamma alumina was prepared; which is applied as the CATALYST in the heavy oil HYDRODESULFURIZATION unit. Extrudates gamma alumina has been devised the boehmite powder; several samples have been utilized to investigate the concentration and the number of acetic acid treatment effects on the textural properties. Textural properties of CATALYST support have been characterized by X-Ray Diffraction, N2-adsorption/desorption techniques, the best results were observed at 25% acetic acid after three times treatments. The active metals (3. 71%Molybdenium &1. 43%Nickle) have been impregnated on the CATALYST support. The prepared CATALYST determined by X-Ray Fluorescence, N2-adsorption/desorption, bench scale reactor test, NH3-Temperature Programmed Desorption and Radial Strength techniques.

In recent years, many studies have been done on reusing waste materials like red mud, because it consists of various oxides like iron oxides, alumina and silica that can be used as support for HYDRODESULFURIZATION CATALYSTs. The common HYDRODESULFURIZATION CATALYSTs are CoMo/Al2O3 and NiMo/Al2O3. Addition of secondary promoter such as zirconia is proposed as a useful solution for increasing CATALYST activity and production of standard fuels. In this paper, NiMo nanoCATALYST supported on activated red mud was prepared by impregnation method containing various amounts of Zr promoter and its catalytic performance was evaluated for HYDRODESULFURIZATION ((HDS)) process of iso diesel and light diesel in the atmospheric pressure. The red mud support along with synthesized nanoCATALYSTs were characterized with XRF, XRD, FESEM, BET and FTIR techniques. Analytical techniques related to NiMo/ZrO2-ARM nanoCATALYSTs characterization revealed that zirconia addition resulted in uniform dispersion of particles on the support surface and destroying of agglomerate, an increase in the active phase and a decrease in the formation of Ni spineless. The catalytic activity of nanoCATALYSTs in the HYDRODESULFURIZATION process showed that NiMo/ZrO2-ARM with 10 wt. % zirconia had the best catalytic activity for iso diesel and 15 wt. % zirconia for light diesel.

In this research, a systematic investigation was carried out to determine kinetics of (HDS) reaction of Iranian gas condensate using a commercial CATALYST (Co-Mo/  g -Al2O3). In this way, process conditions were optimized. Experiments were carried out in a trickle bed micro reactor (10 cc CATALYST) at 280-3400C, 40-50 bar, Liquid hourly space velocity (LHSV) of 1-5 h –1, H2/Oil ratio of 125 nl/l. Prior to the kinetics tests, by some basic tests, mass transfer effects on chemical reactions were evaluated, and it is found that pore diffusion and film diffusion resistances have a slight effect on the kinetics of chemical reaction, within the operating conditions. Hence, kinetics of (HDS) reaction was determined by using thiophene as a reference sulfur component, in the form of power low model. The results indicated that thiophene (HDS) reaction order in gas condensate feed was 1.3. Also, (HDS) reaction activation energy was determined to be 77.55 kj/mol. The results of this kinetics model and its simulation can use in optimization of (HDS) units process conditions and prediction of product specifications with new feeds and different process conditions. It is also useful for designing the reactor of new (HDS) plants.

In Iran, power plants use liquid fuels such as heavy fuel oil (HFO) or mazut to prevent disruption in power generation. The high percentage of sulfur compounds in HFO and the lack of efforts to remove it cause significant damage to the environment. The purpose of this research is performing a techno-economic analysis of the HYDRODESULFURIZATION ((HDS)) process of HFO. The results show that for removing 85% of sulfur compounds from HFO with 3. 5 wt % sulfur compounds at a volume flow rate of 250 m3/h, the total capital investment and the net production cost are 308. 9 million USD and 114. 5 million USD/year respectively. Moreover, the sensitivity analysis indicates that with a 100% increase in the CATALYST loading, the mass percentage of sulfur compounds in the HFO decreases by more than 15%, which adds 6. 4% and 32% to the total capital investment and net production cost respectively. With a 100% increase in the gas-to-oil ratio, the mass percentage of sulfur compounds in the HFO decreases by more than 15. 3%, which adds 43. 8% and 6% to the total capital investment and net production cost respectively. With a 100% increase in the pressure of the (HDS) process, the mass percentage of sulfur compounds in the HFO declines by more than 20. 75%, which adds 43% and 6. 75% to the total capital investment and net production cost respectively. Ultimately, with a 100% increase in the inlet temperature of the beds, the mass percentage of sulfur compounds in the HFO is reduced by more than 5%. Among the effective operational parameters, hydrogen consumption has the greatest impact on net production cost and payback period, and the pressure of the HYDRODESULFURIZATION process has the most significant influence on increasing the total capital investment of the process.

Group VIII B metal oxides supported on gamma-alumina were investigated as CATALYSTs and promoters of MoO3 HYDRODESULFURIZATION catalysis. Superior promotion was observed in PbO promoted CATALYST compared to that of CoO, the typically accepted promoter. Other metal oxides, SnO and Ho2O3 exhibited reasonable HYDRODESULFURIZATION catalysis promotion but lower than for CoO promoted CATALYST.