Study on the in situ desulfurization and viscosity reduction of heavy oil over MoO_(3)–ZrO_(2)/HZSM-5 catalyst

Heavy oil is characterized by high viscosity.High viscosity makes it challenging to recover and transport.HZSM-5,MoO_(3)/HZSM-5,ZrO_(2)/HZSM-5 and MoO_(3)–ZrO_(2)/HZSM-5 catalysts were developed to promote in situ desulfurization and viscosity reduction of heavy oil.The physical and chemical properties of catalysts were characterized by XPS,XRD,TEM,NH3-TPD,etc.The effects of temperature,catalyst type and addition amount on viscosity and composition of heavy oil were evaluated.The results showed that the presence of MoO_(3)–ZrO_(2)/HZSM-5 nanoparticles during aquathermolysis could improve the oil quality by reducing the heavy fractions.It reduced viscosity by 82.56%after the reaction at 280℃ and catalyst addition of 1 wt%.The contents of resins and asphaltic in the oil samples were 5.69%lower than that in the crude oil.Sulfur content decreased from 1.45%to 1.03%.The concentration of H2S produced by the reaction was 2225 ppm.The contents of sulfur-containing functional groups sulfoxide and sulfone sulfur in the oil samples decreased by 19.92%after the catalytic reaction.The content of stable thiophene sulfur increased by 5.71%.This study provided a basis for understanding the mechanism of heavy oil desulfurization and viscosity reduction.

Effects of ZrO_2 on the Performance of CuO-ZnO-Al_2O_3/HZSM-5 Catalyst for Dimethyl Ether Synthesis from CO_2 Hydrogenation

A series of composite catalysts were prepared by the wet mixing method, and the mass ratio of CuO-ZnO-Al2O3-ZrO2 component to HZSM-5 zeolite （molar ratio of SiO2 to Al2O3 being 25） was 2：1. The CuO-ZnO-Al2O3-ZrO2 （CuO/ZnO/Al2O3=3/6/1 by weight） component was prepared by a modified ＇two-step＇ co-precipitation method. The effects of ZrO2 on the performance of CuO-ZnO-Al2O3/HZSMo5 catalyst for dimethyl ether synthesis from CO2 hydrogenation were investigated. It was found that ZrO2 improved the properties of CuO-ZnO-Al2O3/HZSM-5 as a structural promoter.

CO_(2)加氢制二甲醚CuO-ZnO-ZrO_(2)/HZSM-5催化剂研究

采用尿素均匀沉淀法制备一系列不同硅铝比的HZSM-5分子筛复合的CuO-ZnO-ZrO_(2)/HZSM-5(CZZH)催化剂,并在固定床反应装置上探究了催化剂对CO_(2)加氢制二甲醚(DME)的影响。采用XRD、BET和NH_(3)-TPD进行了表征。结果表明:Si/Al=38分子筛复合的CZZH催化剂有最多的中强酸中心,催化剂表现出最好的催化性能,DME的收率为10.8%。

Catalytic kinetics of dimethyl ether one-step synthesis over CeO_2–CaO–Pd/HZSM-5 catalyst in sulfur-containing syngas process

CeO_2–CaO–Pd/HZSM-5 catalyst was prepared for the dimethyl ether(DME) one-step synthesis in a continuous fixed-bed micro-reactor from the sulfur-containing syngas. The catalytic stability over hybrid catalyst of CeO_2–CaO–Pd/HZSM-5 was investigated to ensure that the kinetics experimental results were not significantly influenced by induction period and catalytic deactivation. A large number of kinetic data points(40 sets) were obtained over a range of temperature(240–300 °C), pressure(3–4 MPa), gas hourly space velocity(GHSV)(2000–3000 L·kg^(-1)·h^(-1)) and H_2/CO mole ratio(2–3). Kinetic model for the methanol synthesis reaction and the dehydration of methanol were obtained separately according to reaction mechanism and Langmuir–Hinshelwood mechanism. Regression parameters were investigated by the method combining the simplex method and Runge–Kutta method. The model calculations were in appropriate accordance with the experimental data.

Mass-transfer studies of solid-base catalyst-aided CO_(2) absorption and solid-acid catalyst-aided CO_(2) desorption for CO_(2) capture in a pilot plant using aqueous solutions of MEA and blends of MEA-MDEA and BEA-AMP

Mass-transfer studies of catalyst-aided CO_(2) absorption and desorption were performed in a full-cycle,bench-scale pilot plant to improve CO_(2) absorption using 5M MEA,5M MEA-2M MDEA and 2M BEA-2M AMP.A solid-base catalyst,K/MgO,and an acid catalyst,HZSM-5,were used to facilitate absorption and desorption,respectively.Absorption and desorption mass-transfer performance was presented in terms of the overall mass-transfer coefficient of the gas side(KGav)and liquid side(K_(L)a_(v)),respectively.For non-catalytic runs,the highest K_(G)a_(V) and K_(L)a_(V) were 0.086 Kmol m^(3).kPa.hr and 0.7851 hr for 2M BEA-2M AMP solvent.The results showed 38.7% KGav and 23.6% K_(L)a_(v) increase for 2M BEA-2M AMP with only HZSM-5 catalyst in desorber and a 95% K_(G)a_(V) and 45% K_(L)a_(V) increase for both K/MgO catalyst and HZSM-5 catalyst.This was attributed to the role of K/MgO in bonding loosely with CO_(2) and making it available for the amine reaction.

Active Center Changed: Disproportionation Mechanism for Preparing Dimethyldichlorosilane Catalyzed by Core(4T)-shell Catalyst

Dimethyldichlorosilane is a basic raw material for preparing a variety of organosilicon materials.The disproportionation method to synthesize it can solve the problem brought by direct synthesis.The B3LYP/6-31G and MP2/6-311++G(3df,2pd) methods were used to calculate the mechanism of the reaction catalyzed by localized core(4 T)-shell catalyst.The energy barriers of the rate-determining steps of the main reaction at different active sites 1(5)~4 in the HZSM-5(4T)@γ-Al2O3 catalyst were 165.88,129.99,118.66 and 145.55 kJ·mol-1,respectively,and those in the side reaction are 131.98,146.28,146.53 and 164.17 kJ·mol-1,separately.The active site No.3 was the easiest one to participate in the catalytic reaction.The energy barriers of the rate-determining steps of the main reaction catalyzed by the AlCl3/HZSM-5(4T)@γ-Al2O3 catalyst,involving configurations a and b,are 105.12 and 110.39 kJ·mol-1,respectively,and those of the side reaction are 144.26 and 159.55 kJ·mol-1,respectively.Both configurations produced dimethyldichlorosilane mainly,and configuration a is easier to catalyze the reaction process.And according to the bond order and locality analysis,the catalytic activity order was:configuration a>configuration b.This conclusion matched with the reaction energy barrier analysis.The AlCl3/HZSM-5(4T)@γ-Al2O3 catalyst had a better catalytic activity than HZSM-5(4T)@γ-Al2O3.The active center of the reaction system of HZSM-5(4T)@γ-Al2O3 was proton,Bronsted acidic center,and that of AlCl3/HZSM-5@γ-Al2O3 could be Lewis acidic center.The source of the Lewis acidic center was the multi-center bond formed by the delocalization of peripheral electrons of the atoms.The frontier orbital theory confirmed the mechanism and good selectivity of the reaction.