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Introduction to Chemistry of Diesel Fuels
Published in Chunshan Song, Chang S. Hsu, Isao Mochida, Chemistry of Diesel Fuels, 2020
New and improved catalysts and different processing schemes are among the subjects of active research on deep HDS[71,73,75]. For example, some recent studies examined carbon-supported CoMo catalysts for deep HDS[92,93]. Binary oxide supports such as TiO2-Al2O3 have been examined for making improved HDS catalysts[105, 106]. In 1992, novel mesoporous molecular sieve MCM-41 was invented by Mobil researchers[107,108]. MCM-41 has high surface area, large pore volume and uniform mesopore with pore diameter ranging from 15 to 100 Å. Al-MCM-41 has been synthesized with improved aluminum incorporation into framework [109,110]and applied to prepare Co-Mo/MCM-41 for deep HDS of diesel fuels[111–114] and for HDS of petroleum resid[115]. Compared to CoMo/Al2O3, higher activity for HDS has been observed for Co-Mo/MCM-41 with a higher metal loading.
Microporous and Mesoporous Solids
Published in Elaine A. Moore, Lesley E. Smart, Solid State Chemistry, 2020
Elaine A. Moore, Lesley E. Smart
In 1992, scientists at Mobil Research and Development Corporation developed a family of silicate and aluminosilicate materials (M41S) that had pores in the mesoporous range. The mesoporous material that has received most attention so far is MCM-41 (Mobil Crystalline Materials). It has a highly ordered hexagonal array of uniformly sized mesopores and can have a huge surface area of 1200 m2 g−1. It is made by a templating technique, where the silicate or aluminosilicate walls of the mesopores, instead of forming around a single molecule or ion, form around an assembly of molecules known as a micelle. In a solution of silicate or silicate and aluminate anions, cationic long-chain alkyl trimethylammonium surfactants ([CH3(CH2)n(CH3)3N+] X−) form rod-like micelles (Figure 7.25), with the hydrophobic tails clustering together inside the rods and the cationic heads forming the outside; these silicate/aluminate ions form a cladding around the micelles. The silicate-coated micelles pack together along the axes of the rods, earning the synthesis technique the name liquid crystal templating; under hydrothermal conditions, this mesoporous structure precipitates out of the solution. The calcination of the filtered solid in air at temperatures up to 700°C removes the template and produces the mesoporous solid. As we would expect, the alkyl chain length determines the size of the pores; where n = 11, 13, and 15, the pore diameters are 300, 340, and 380 nm, respectively.
Microporous and Mesoporous Molecular Sieves
Published in Rolando M.A. Roque-Malherbe, Adsorption and Diffusion in Nanoporous Materials, 2018
The adsorption characteristics of MCM-41 for polar molecules greatly depend on the concentrations of surface silanol groups (SiOH) [184,193–196]. It has been demonstrated that several types of SiOH groups exist over MCM-41 surfaces, which can be qualitatively and quantitatively determined by a number of techniques [184,193–196]. Those SiOH groups allow various accomplishments in the modification of MCM-41 for catalysis, adsorption, and novel composites [196]. For example, a sorption separation process using modified MCM-41 for purification of water has been proposed [197].
Benzene hydrogenation over polydopamine-modified MCM-41 supported Ruthenium-Lanthanum catalyst
Published in Inorganic and Nano-Metal Chemistry, 2018
Hongguang Liao, Yanjuan Xiao, Xiaoguang Yu, Xuanyan Liu, Hongmei Zhong, Meidong Liang, Haoyan He
MCM-41 was prepared by a hydrothermal synthesis method. Typically, CTAB (2.76 g) was dissolved in the deionized water (80 g), and TMB (2.74 g) was added to the solution. After the pH of the solution was adjusted to 11 by ammonia solution (25 wt%), TEOs (5 g) was added slowly to the solution over a period of 10 min with vigorous stirring and a white gel was obtained. And then 0.1 mol/L of NaAlO2 aqueous solution (12 mL) was added dropwise into the gel. The mixture was stirred for 1 h followed by transferring to a Teflon-lined autoclave for crystallization at 413 K for 2 days. The aged sample was filtered and washed with deionized water and ethanol. Finally, the sample was dried at 363 K for 12 h and calcinated at 1023 K for 5 h in air with a heating rate of 1 K min−1.
Nickel(II) complex anchored on MCM-41, a reusable catalyst for the synthesis of benzimidazole and quinazolinone
Published in Journal of Coordination Chemistry, 2022
Udai P. Singh, Saurabh Sharma, Arti Malik
The nitrogen adsorption–desorption isotherms for MCM-41 and MCM-41@PDCA-Ni are shown in Figure 4. For MCM-41, a type-IV isotherm with hysteresis loop, characteristic of mesoporous structure, was observed (Figure 4a) [57]. BET surface area and pore volume of MCM-41 were 1065.19 m2g−1 and 0.71 cm3g−1, respectively. In comparison to MCM-41, MCM-41@PDCA-Ni exhibited considerably lower N2 uptake (BET surface area 458.73 m2g−1 and pore volume 0.26 cm3 g−1) (Figure 4b). A decrease in the physical parameters may be due to dispersion and deposition of nickel(II) complex in the pore channels of MCM-41 [58–60].
Green synthesis of benzimidazole derivatives under ultrasound irradiation using Cu-Schiff base complexes embedded over MCM-41 as efficient and reusable catalysts
Published in Journal of Coordination Chemistry, 2020
M. Bharathi, S. Indira, G. Vinoth, T. Mahalakshmi, E. Induja, K. Shanmuga Bharathi
Among mesoporous silica materials, MCM-41 has special properties like high thermal stability, high pore volume, high surface area and well-ordered hexagonal arrangement [37]. Hence MCM-41 is a suitable support for anchoring metal complexes. Metal ions such as copper, nickel [38], zinc, manganese, cobalt, etc., in mesoporous silica framework, have made contributions in heterogeneous catalysis due to their low toxicity and low cost. Anchoring of different ligands into the hexagonal channels can be easily modified in the walls of the porous system of MCM-41 [39, 40] and allows tuning catalytic activity.