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149 results on '"Huirache-Acuña, R."'

31. Hydrodesulfurization on Supported CoMoS2 Catalysts Ex Ammonium Tetrathiomolybdate: Effects of Support Morphology and Al Modification Method.

Author

Huirache-Acuña, R., Navarro Yerga, R. M., and Pawelec, B.

Subjects
*CATALYSTS, *CATALYST supports, *MESOPOROUS silica, *BATCH reactors, *AMMONIUM, *FISCHER-Tropsch process, *DESULFURIZATION, *MOLYBDENUM sulfides
Abstract

In this work, Co-promoted MoS2 catalysts supported on Al-modified mesoporous silica (HMS and SBA-16) have been prepared by the decomposition of ammonium tetrathiomolybdate and cobalt nitrate precursors in a H2S/H2 gas mixture. The effects of the support morphology and Al incorporation method (one-pot synthesis vs. support's grafting) on the catalyst activity were investigated in the reaction of hydrodesulfurization (HDS) of dibenzothiophene (DBT) conducted in a high-pressure batch reactor at 350 °C and total H2 pressure of 3.3 MPa. The physical and chemical characterization of the oxide precursors and spent catalysts was studied by a variety of several techniques (N2 adsorption–desorption, XRD, SEM, EDS, 27Al MAS NMR, Raman, TG/DTA and DRS UV–vis). The MoS2 phase of all catalysts exhibits similar size (about 2.8 nm) and stacking layers (4). Activity tests showed that CoAT/HMS-Al was most active and selective toward direct desulfurization (DDS) reaction pathway among the catalysts studied. Its catalytic response was similar to that of CoMo/γ-Al2O3 catalyst activated by reductive sulfiding. A linear correlation was found between DBT conversion at a reaction time of 5 h and the specific surface area and mean pore diameter of the catalysts. The best DBT HDS activity showed CoAT/HMS-Al catalyst having the best textural properties among the catalysts studied. Modification of SBA-16 with Al3+ ions by the one-step synthesis method rendered the catalyst more active in the HDS reaction than its modification by grafting. [ABSTRACT FROM AUTHOR]

Published
2022
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42. Dosimetric properties of KMgF3:Tb + PTFE

Author

Ramírez-Romero, M.I., primary, García-Salinas, L., additional, Villicaña-Méndez, M., additional, Huirache-Acuña, R., additional, Apolinar-Cortés, J., additional, and González, P.R., additional

Published
2018
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43. Unsupported CoNixMo sulfide hydrodesulfurization catalysts prepared by the thermal decomposition of trimetallic tetrabutylammonium thiomolybdate: effect of nickel on sulfur removal.

Author

Cervantes, J. A. Medina, Huirache-Acuña, R., de León, J. N. Díaz, Moyado, S. Fuentes, Cruz-Reyes, J., and Alonso-Núñez, G.

Abstract

Herein we report the synthesis of unsupported bimetallic CoMo and trimetallic CoNiMo sulfide catalysts prepared by thermal decomposition (ex situ activation) of carbon-containing precursors and varying the nickel concentration for the hydrodesulfurization (HDS) of dibenzothiophene. The catalysts prepared were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma mass spectrometry and BET surface area measurements. The results from the characterization showed that the addition of an alkyl chained precursor results in non-porous catalysts with low surface area and high carbon content, which negatively affects the formation of crystalline phases such as molybdenum sulfide and their performance in the HDS reaction. Furthermore, the addition of nickel has a negative effect on the catalysts since it was observed that when it was added, the reaction rate values decreased and the catalyst with the highest catalytic activity turned out to be the CoMo catalyst. Although nickel catalysts generally have more affinity for hydrogenation reactions, unsupported trimetallic catalysts showed a preference for the direct desulfurization pathway. [ABSTRACT FROM AUTHOR]

Published
2020
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49. Trimetallic RuxMoNi Catalysts Supported on SBA-15 for the Hydrodesulfurization of Dibenzothiophene.

Author

Torres-García, N.L., Huirache-Acuña, R., Zepeda-Partida, T.A., Pawelec, B., Fierro, J.L.G., Vázquez-Salas, P.J., Maya-Yescas, R., and Rivera-Garnica, J.M.

Subjects
*CATALYST supports, *HYDROTREATING catalysts, *CATALYTIC activity, *BASE catalysts, *CHELATING agents, *DESULFURIZATION
Abstract

In this work, novel trimetallic catalysts based on transition metal sulphides (Ru, Mo and Ni) supported on SBA-15 were synthesized. Citric acid (CA) was used as chelating agent in order to enhance the dispersion of the active phase and minimize the metal-support interaction. Sulfided catalysts were evaluated in the reaction of hydrodesulfurization (HDS) of dibenzothiophene (DBT) at 320 °C and 54.5 atm of total H2 pressure. The effects of different Ru/(Ni + Mo) atomic ratios on the active phase were studied. The catalysts were characterized using Micro-Raman spectroscopy, DRIFTS, XRD, XPS, HR-TEM and SEM techniques. Results have shown that there was a better dispersion of the metallic phases, which improves the physicochemical properties of the catalysts, increasing the catalytic activity. The trimetallic RuxMoNi catalyst with the lowest atomic ratio, have shown superior catalytic activity compared to their higher atomic ratio counterparts. The interaction of the chelating agent improved the catalytic activity, which was superior to that observed for NiMo based catalysts, considered one of the most active hydrotreating catalysts. [ABSTRACT FROM AUTHOR]

Published
2019
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