Mexican Institute of Petroleum

About: Mexican Institute of Petroleum is a government organization based out in Mexico City, Mexico. It is known for research contribution in the topics: Catalysis & Asphaltene. The organization has 3273 authors who have published 4170 publications receiving 87269 citations.

Preparation of Ni/ZrO2–SO42− catalysts by incipient wetness method: effect of nickel on the isomerization of n-butane

Abstract: A series of Ni-promoted sulfated zirconia catalysts with different nickel concentration (from 1 to 9.6 wt.%) were prepared by incipient wetness method. Ni and SO 4 2− promoters were co-impregnated to a parent zirconium hydroxide by a solution of Ni(NO 3 ) 2 ·6H 2 O in H 2 SO 4 . After calcination at 948 K, the solids isomerized n -butane at 338 K. Up to 4.5 wt.% Ni content, nickel increases activity of ZrO 2 –SO 4 2− , afterwards, the catalytic activity decreases. The temperature-programmed desorption of ammonia (TPD-NH 3 ) and IR of pyridine adsorbed results show that enhanced activity cannot be completely explained in function of a higher acid strength. The increase of the isomerizating activity is better explained in terms of a bimolecular mechanism, as proposed by Guisnet et al. [M.R. Guisnet, Acc. Chem. Res. 23 (1990) 392], involving olefins as intermediates. In this mechanism, Ni causes an enhancement in the surface concentration of olefins. In spite of the relatively high Ni concentration, X-ray diffraction results showed no evidence of any NiO phase due to this oxide is well-dispersed on the surface of ZrO 2 –SO 4 2− in form of small particles. The inhibition of isomerizating properties of the catalysts when hydrogen was present in the reactor feed confirmed this bimolecular mechanism. Interestingly, unpromoted ZrO 2 –SO 4 2− exhibited also the usual induction period observed on nickel-promoted sulfated zirconia catalysts. Then, this bimolecular mechanism for the n -butane isomerization could also apply in the unpromoted zirconia sulfate catalyst.

Cumene cracking functionalities on sulfided Co(Ni)Mo/TiO2-SiO2 catalysts

Abstract: Cumene cracking reaction was carried out on pure support as well as sulfided Mo, CoMo, and NiMo catalysts in a plug flow micro-reactor at 400 °C and atmospheric pressure. Catalytic activity was studied as a function of Mo content, promoter content (Co, Ni), and support composition [Ti/(Ti+Si)=0.0, 0.15, 0.30, 0.45, 0.70, 1.0]. Surface acid–base properties of pure supports were measured with 2-propanol decomposition, showed that the supports were acidic in nature, the acidic character increases with increasing TiO 2 content in SiO 2 . Techniques used for characterization were BET specific surface area (SSA), pore volume, X-ray diffraction, CO 2 chemisorption, and low temperature oxygen chemisorption (LTOC). CO 2 chemisorption on sulfided catalysts showed a strong decrease in the amount of CO 2 adsorption as a function of metal loading. The sulfided-supported catalysts exhibited better cracking activity in presence of hydrogen, which suggests that sulfided molybdenum phases were responsible for cumene cracking activity. The LTOC and catalytic activity results showed similar trends with variation of molybdenum content which indicated that the cracking activity of Mo and CoMo catalysts has significant contribution from the supported phases. The cumene cracking activity over supported catalysts is attributed to the Bronsted (S–H) sites like sulfhydryl groups. Variation of support composition strongly affects the catalytic cracking activity which decreases with increasing TiO 2 content in SiO 2 .