Showing papers on "MCM-41 published in 2019"
TL;DR: In this paper, a new organometallic complex of palladium was supported on its inner surface (Pd-imi@MCM-41/Fe3O4), which was applied as highly efficient, heterogeneous and magnetically recoverable nanocatalyst in the various C C coupling reactions such as Suzuki and Mizoroki-Heck reactions under phosphine-free conditions at atmospheric pressure.
48 citations
TL;DR: In this paper, the surface of magnetic MCM-41 nanoparticles was modified by 3-aminopropyltriethoxysilane (APTES) and further, 1-methyl imidazole was anchored on their surface using cyanuric chloride as a linker.
Abstract: In this study, the surface of magnetic MCM-41 nanoparticles (MCM-41/Fe3O4) was modified by 3-aminopropyltriethoxysilane (APTES) and further, 1-methyl imidazole was anchored on their surface using cyanuric chloride as a linker. Then, Pd2+ ions were immobilized on the surface of the modified MCM-41/Fe3O4 (Pd-imi-CC@MCM-41/Fe3O4), and its application was studied as a magnetically recyclable nanocatalyst in carbon–carbon coupling reactions between a wide range of aryl halides and butyl acrylate, methyl acrylate, acrylonitrile, phenylboronic acid, or 3,4-difluorophenylboronic acid under the conditions of a phosphine-free ligand and an air atmosphere. This catalyst has the advantages of both the Fe3O4 nanoparticles and mesoporous MCM-41. The structure of the catalyst was characterized via TEM, SEM, EDS, WDX, N2 adsorption–desorption isotherm, XRD, TGA, FT-IR, and AAS. Also, the recovered catalyst was characterized via SEM, AAS and FT-IR. All the products from the carbon–carbon coupling reaction were obtained with excellent yields and high TON and TOF values, which indicate the high efficiency and activity of this catalyst. The selectivity of this catalyst was studied with various aryl halides bearing different functional groups. Furthermore, the heterogeneity and stability of Pd-imi-CC@MCM-41/Fe3O4 was studied via AAS, and leaching and poisoning tests. According to the results, this heterogeneous catalyst can be reused several times.
47 citations
TL;DR: In this article, a catalytic method is presented for the synthesis of aromatic carbamates from aromatic amines using dimethyl carbonate instead of phosgene as a green and safe reaction process.
47 citations
TL;DR: The study shows that catalytic co-pyrolysis is a complex reaction process, and many reaction conditions could affect the final reaction results.
46 citations
TL;DR: In this paper, the impregnation method was deployed to prepare mono and bimetallic catalyst Nix-Co(10-x) loaded on MCM-41 nanoparticles as the catalyst for the catalytic steam reforming of ethanol (SRE).
Abstract: Catalytic Steam reforming of ethanol (SRE) is a promising method for the generation of H2 as a clean carrier of energy. In this study, the impregnation method was deployed to prepare mono and bimetallic catalyst Nix-Co(10-x) (x = 10, 9, 8, 5 and 0) loaded on MCM-41 nanoparticles as the catalyst for the SRE reaction. The characteristics of the synthesized catalysis were identified using BET, XRD, EDS, FESM, and TGA/DTA analysis in a fixed bed micro-reactor, the gases were constantly monitored by using gas chromatography (GC). The purpose of this project is to optimize the reaction conditions using synthesized catalysts and to find the best catalyst. The effects of reaction temperature (420–500 °C) and molar ratios of steam to ethanol (S/E = 2, 3 and 5) were studied in detail over this catalyst. According to the results, the performance of bimetallic catalysts is very high compared to mono metal catalyst. Between mono metal catalysts Nickel was active rather than Cobalt. Ni9 Co1/MCM-41 catalysts displayed the best catalytic performance, so that the conversion of ethanol was 90% and highest hydrogen yield of 80% were achieved at the temperature of 490°C, S/E = 5 and under the atmospheric pressure.
43 citations
TL;DR: In this paper, a mesoporous catalyst support material was synthesized by incorporation of zirconia into the structure of MCM-41 through a one-pot procedure.
38 citations
TL;DR: In this paper, the pyrolysis-catalytic upgrading of vulcanized rubbers with metal modified zeolites was performed in order to improve oil quality and decrease sulfur content in Pyrolytic oils simultaneously.
38 citations
TL;DR: The mesoporous aluminosilicates Al-HMS (Si/Al) and Al-MCM-41 types were synthesized via the neutral templating pathway and used as supports for Ni-Mo sulfide catalysts, prepared by standard incipient wetness co-impregnation technique followed by sulfidation procedure.
37 citations
TL;DR: In this article, a soft-templating strategy was used to obtain the Ni-containing MCM-41-carbon composites using nickel nitrate as an additive, which showed enhanced catalytic activity toward nitrophenol reduction obeying the zero-order kinetics.
Abstract: MCM-41–carbon composites were obtained by soft-templating strategy by adding resorcinol and formaldehyde as carbon precursors during the synthesis of MCM-41. The synthesis of these composites was optimized until mesoporous MCM-41 domains remained highly ordered and the overall specific surface area and pore volume remained relatively high. The one-pot synthetic procedure was further extended to obtain the Ni-containing MCM-41–carbon composites using nickel nitrate as an additive. A homogeneous distribution of nickel nanoparticles in the composites was achieved by adding histidine to the reaction mixture, which was able to form a complex with nickel ion. Carbonization of organic components in the composites produced carbon that was responsible for in situ reduction of nickel(II) to metallic nickel (Ni0) at elevated temperatures, eliminating the post-synthesis reduction step carried out in the presence of hydrogen gas or other reducing agent. The resulting composites showed enhanced catalytic activity toward nitrophenol reduction obeying the zero-order kinetics. Three unique features of the resulting composites, namely mesoporous channels of MCM-41, carbon-induced in situ reduction of Ni ions to metallic Ni nanoparticles, and abundance of highly active Ni sites due to high dispersion of Ni0, make this strategy applicable for the synthesis of other transition metal-based catalysts. XRD and STEM analyses revealed a homogeneous distribution of nickel nanoparticles in the composites without significant distortion of their ordered mesoporosity.
37 citations
TL;DR: In this paper, ZrO2-promoted Cu ZnO catalysts were synthesized using MCM-41 as support material and applied to the methanol steam reforming (MSR) reaction.
36 citations
TL;DR: In this paper, the first report of Cu-based heterogeneous catalysts on mesoporous materials for the isomerization reaction of monoterpenes epoxides was presented.
Abstract: Fe and Cu based heterogeneous catalysts were evaluated in the isomerization reaction of α- and β-pinene epoxides. The metals were incorporated on SBA-15 and MCM-41 using incipient wetness impregnation procedure and the materials were characterized by XRD, Raman spectroscopy, BET analysis, NH3-TPD, TEM and XPS. 1.4/Fe-MCM-41 was the catalyst with the highest TON value (364) and α-pinene epoxide conversion (73%) with a campholenic aldehyde selectivity of 59%, while from β-pinene epoxide 1.4/Fe-SBA-15 was the material with the highest TON (299) and selectivity (100%) to myrtanal with a substrate conversion of 60%. Cu based materials presented lowest TON value for the rearrangement of β-pinene epoxide than using α-pinene epoxide as substrate. Besides, it was elucidated that the formation of campholenic aldehyde and myrtanal is function of the presence of metal oxides, mean particle diameter and the strength of acidity; moreover, the most active catalysts did not present leaching under the reaction conditions. 1.4/Fe-MCM-41 can be used until five times without loss of catalytic activity with α pinene epoxide. Based on the characterization and different products synthetized, a reaction mechanism for the rearrangement reaction of α-pinene epoxide is proposed. This is the first report of Cu heterogenized on mesoporous materials for the isomerization reaction of monoterpenes epoxides.
TL;DR: In this paper, a new synthetic method for preparing confined Ni/MCM-41 catalysts, which impede the sintering of metal nanoparticles (NPs) and coke deposition at high temperatures, enabling them to be successfully applied to methane dry reforming.
TL;DR: In this article, a novel magnetic mesoporous MCM41 supported boric acid [Fe3O4@MCM-41-OB(OH)2] is prepared, characterized and its catalytic application is investigated.
Abstract: A novel magnetic mesoporous MCM-41 supported boric acid [Fe3O4@MCM-41-OB(OH)2] is prepared, characterized and its catalytic application is investigated. The Fe3O4@MCM-41-OB(OH)2 was prepared through modification of magnetic iron oxide nanoparticles with MCM-41 silica followed by treatment with boric acid. This nanocomposite was characterized using Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). The Fe3O4@MCM-41-OB(OH)2 was used as effective nanocatalyst in the one-pot Biginelli condensation of aldehydes with urea and alkylacetoacetates at 50 °C under ultrasonic conditions. The corresponding products were obtained in high yields (88–96%) at short times (15–30 min). The designed catalyst was successfully reused and recovered at least nine times without significant decrease in its stability and efficiency.
TL;DR: In this article, the effect of sequence addition of silica and chromium precursors of one-pot synthesis of Cr/MCM-41catalysts on their structural properties and catalytic performance for oxidative dehydrogenation of ethane (ODH) to ethylene using CO2 was investigated.
TL;DR: In this article, mesoporous vanadosilicates were used as acidic catalysts in the ketalization of glycerol with acetone for solketal formation, and the catalytic activity was dependent on the amount of acid sites, based on three types of vanadium oxide species: (i) isolated or (ii) oligomeric vanadium species inserted in the silica framework, i.e. -Si-O-(V-O-V-V)n, where n = 1 and n < 1, respectively, and (iii) surface van
TL;DR: In this article, the authors synthesized Si-MCM-41 molecular sieves from a waste material (rice husk ash - RHA) and compared it with Si-Mcm-41 synthesized from a commercial silica source (tetraethylorthosilicate - TEOS).
TL;DR: The particle size and size distribution of the Mg/CeM (Si/CE = 10) nanocatalyst demonstrated the highest conversion of 94.3% at the end of seventh cycle which demonstrated its significant stability.
TL;DR: In this paper, an indexed isomerization factor (IIF) was deduced based on the experimental results, which is correlated with the physical properties of the supports, and the results indicated that the isoheptane yield of the catalysts is strongly dependent on the support.
TL;DR: In this article, a mesoporous MCM-41 silica was designed for ultralow concentration and its performance was investigated at catalysts with high catalysts activity at ultralOW concentration.
Abstract: The study of catalysts activity at ultralow concentration is of prime importance for the development of more sustainable catalytic processes. In this work, we designed a mesoporous MCM-41 silica wi...
TL;DR: A series of chromium oxide catalysts supported on the mesoporous Ce-MCM-41 molecular sieves with different (Si/Ce) molar ratios have been synthesized by hydrothermal/impregnation method and compared with the catalysts treated by plasma energy as mentioned in this paper.
TL;DR: In this article, the authors reported the synthesis of hexagonal and ordered aluminum-containing mesoporous silica materials (Al-MCM-41) from natural perlite mineral without addition of silica or aluminum reagents.
Abstract: Silica reagents are expensive and toxic for use in the synthesis of mesoporous silica materials. It is imperative to take an interest in green silicon sources. In this paper, we report the synthesis of hexagonal and ordered aluminum-containing mesoporous silica materials (Al–MCM–41) from natural perlite mineral without addition of silica or aluminum reagents. A pretreatment process involving acid leaching, alkali leaching, and strongly acidic cation exchange resins treatment was critical to obtain silicon and aluminum sources from natural perlite mineral. The Al–MCM–41 material was synthesized via a hydrothermal reaction with hexadecyl trimethyl ammonium bromide (CTAB) as the template and subsequent calcination. The resulting mesophase had a hexagonal and ordered mesoporous structure, confirmed by small-angle X-ray diffraction (SAXRD) and transmission electron microscopy (TEM). Al–MCM–41 material had a high Brunauer–Emmet–Teller (BET) surface area of 1024 m2/g, pore volume of 0.72 cm3/g and an average pore diameter of 2.8 nm with a pore size distribution centered at 2.5 nm. The thermal behavior of the as-synthesized samples during calcination was investigated by thermogravimetry (TG) and differential thermogravimetry (DTG) analysis. The Al–MCM–41 material showed a negative surface charge in aqueous solution with the pH value ranging from 2 to 13. The variations of chemical structures from natural perlite to Al–MCM–41 were traced by wide-angle X-ray diffraction (WAXRD) and Fourier-transform infrared spectroscopy (FTIR). A proposed mechanism for the synthesis of hexagonal and ordered mesoporous silica materials from natural perlite is discussed.
TL;DR: HZSM-5/MCM-41 molecular sieve catalysts with well-defined micro/mesoporous structures were synthesized and showed high performance for selective synthesis of triacetin via the esterification reaction of glycerol with acetic acid.
TL;DR: The obtained results revealed that the conversion and the quality of produced biodiesel were increased significantly by increasing Ce amount of catalysts up to Si/Ce = 25 and also the sonicated sample represented a better reusability compare to non-sonicated one.
TL;DR: In this article, a grafting method to synthesise Ti-doped MCM-41 mesoporous supports and their respective Zn catalysts was investigated, and the structure and dispersion of titanium species for the as-synthesised materials and their influence on the catalytic performance of Zn catalyst in the acetylene hydration reaction were systematically studied.
TL;DR: In this article, the effects of system factors, such as pH and the solid-liquid ratio, on the performance of the adsorption process were discussed, and the thermodynamics and kinetics were also explored.
TL;DR: In this article, a bifunctional Ni-HPMo/Fe3O4@Al-MCM-41 catalyst was used for the liquefaction of switchgrass in isobutanol/water mixed solvents.
TL;DR: In this paper, the most active mesoporous silica catalysts with different Ti contents were prepared by the sol-gel method, whereby the molar ratios of silicon to titanium in the crystallization gel amounted to, respectively, 40:1, 30: 1, 20: 1 and 10:1.
Abstract: Titanium-containing mesoporous silica catalysts with different Ti contents were prepared by the sol–gel method, whereby the molar ratios of silicon to titanium in the crystallization gel amounted to, respectively, 40:1, 30:1, 20:1 and 10:1. The produced Ti-MCM-41 materials were characterized by the following instrumental methods: XRD, UV-Vis, FT-IR, SEM, and XRF. Textural parameters were also determined for these materials by means of the N2 adsorption/desorption method. The activities of these catalysts were investigated in the α-pinene isomerization process. The most active catalyst was found to be the material with the molar ratio of Si:Ti equal to 10:1, which contained 12.09 wt% Ti. This catalyst was used in the extended studies on the α-pinene isomerization process, and the most favorable conditions for this reaction were found to be temperature of 160 °C, reaction time of 7 h, with the catalyst composition of 7.5 wt% relative to α-pinene. These studies showed that the most active catalyst, at the best reaction conditions, allowed for the attainment of 100% conversion of α-pinene over a period of 7 h. After this time the selectivities (in mol%) of the main products were as follows: camphene (35.45) and limonene (21.32). Moreover, other products with lower selectivities were formed: γ-terpinene (4.38), α-terpinene (8.12), terpinolene (11.16), p-cymene (6.61), and α-phellandrene (1.58).
TL;DR: In this paper, a new Ni-MCM-41 was used as an efficient catalyst in the synthesis of benzimidazole derivatives through the oxidative condensation of an aromatic aldehyde with o-phenylenediamine under mild conditions with glycerol as high potential and alternative green solvent.
Abstract: A Nickel(II) Schiff-base complex was anchored on hexagonal mesoporous MCM-41 to prepare a new catalyst. The prepared catalyst has been characterized by FT-IR, UV–DRS, small angle-XRD, SEM–EDX, HR-TEM, N2 adsorption and desorption, ICP-AES, 1H and 13C-NMR. The newly synthesized Ni–MCM-41 is used as an efficient catalyst in the synthesis of benzimidazole derivatives through the oxidative condensation of an aromatic aldehyde with o-phenylenediamine under mild conditions with glycerol as high potential and alternative green solvent. It is found out that the yields of the products were good. Notably, both catalyst and solvent were recovered and reused upto four cycles without any significant loss in the yield. The catalytic efficiency of the catalyst was compared to that of some other reported catalysts and discussed.
TL;DR: In this paper, a novel photocatalyst NiCr2O4/Al-MCM-41, using AlMCM41 zeolite as a support loaded with NiCr 2O4 was successfully prepared by a facile sol-gel method and followed by calcination at 700°C.
TL;DR: The use of H-ZSM-5 and Al-MCM-41 in a two-stage system of mesoporous and microporous catalysts has been proved to improve the quality of bio-oil as discussed by the authors.
Abstract: The use of H-ZSM-5 and Al–MCM-41 in a two-stage system of mesoporous and microporous catalysts has been proved to improve the quality of bio-oil. Information about biomass pyrolysis kinetics is imp...