scholarly journals MCM-41 Supported Co-Based Bimetallic Catalysts for Aqueous Phase Transformation of Glucose to Biochemicals

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 843 ◽  
Author(s):  
Somayeh Taghavi ◽  
Elena Ghedini ◽  
Federica Menegazzo ◽  
Michela Signoretto ◽  
Delia Gazzoli ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Bimetallic Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Mesoporous Structure ◽  
Acid Sites ◽  
Weak Acid ◽  
Reaction Conditions ◽  
Temperature Programmed ◽  
Mcm 41

The transformation of glucose into valuable biochemicals was carried out on different MCM-41-supported metallic and bimetallic (Co, Co-Fe, Co-Mn, Co-Mo) catalysts and under different reaction conditions (150 °C, 3 h; 200 °C, 0.5 h; 250 °C, 0.5 h). All catalysts were characterized using N2 physisorption, Temperature Programmed Reduction (TPR), Raman, X-ray Diffraction (XRD) and Temperature Programmed Desorption (TPD) techniques. According to the N2-physisorption results, a high surface area and mesoporous structure of the support were appropriate for metal dispersion, reactant diffusion and the formation of bioproducts. Reaction conditions, bimetals synergetic effects and the amount and strength of catalyst acid sites were the key factors affecting the catalytic activity and biochemical selectivity. Sever reaction conditions including high temperature and high catalyst acidity led to the formation mainly of solid humins. The NH3-TPD results demonstrated the alteration of acidity in different bimetallic catalysts. The 10Fe10CoSiO2 catalyst (MCM-41 supported 10 wt.%Fe, 10 wt.%Co) possessing weak acid sites displayed the best catalytic activity with the highest carbon balance and desired product selectivity in mild reaction condition. Valuable biochemicals such as fructose, levulinic acid, ethanol and hydroxyacetone were formed over this catalyst.

Transition metal/metal oxide modified MCM-41 for pollutant degradation and hydrogen energy production: a review

RSC Advances ◽  
2015 ◽  
Vol 5 (102) ◽  
pp. 83707-83724 ◽  
Author(s):  
Dipti Prava Sahoo ◽  
Dharitri Rath ◽  
Binita Nanda ◽  
K. M. Parida
Keyword(s):  
Catalytic Activity ◽  
Metal Oxide ◽  
Energy Production ◽  
High Surface ◽  
High Surface Area ◽  
Hydrogen Energy ◽  
Pollutant Degradation ◽  
Metal Metal ◽  
Catalytic Applications ◽  
Mcm 41

Metal/metal oxide modified MCM-41 materials are suitable for various catalytic applications. The high surface area, mesoscopic pore size and tunable pore volume of the materials play a key role in enhancing the catalytic activity.

scholarly journals MIL-101(Cr) for CO2 Conversion into Cyclic Carbonates, Under Solvent and Co-Catalyst Free Mild Reaction Conditions

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 453
Author(s):  
Emmanuelia Akimana ◽  
Jichao Wang ◽  
Natalya V. Likhanova ◽  
Somboon Chaemchuen ◽  
Francis Verpoort
Keyword(s):  
Ring Opening ◽  
High Surface ◽  
High Surface Area ◽  
Strong Acid ◽  
Catalytic Performance ◽  
Acid Sites ◽  
Cyclic Carbonates ◽  
Reaction Conditions ◽  
Co Catalyst ◽  
Strong Acid Sites

Mild reaction conditions (nearly room temperature and atmospheric CO2 pressure) for the cycloaddition of CO2 with epoxides to produce cyclic carbonates were investigated applying MIL-101(Cr) as a catalyst. The MIL-101 catalyst contains strong acid sites, which promote the ring-opening of the epoxide substrate. Moreover, the high surface area, enabling the adsorption of more CO2 (substrate), combined with a large pore size of the catalyst is essential for the catalytic performance. Additionally, epoxide substrates bearing electron-withdrawing substituents or having a low boiling point demonstrated an excellent conversion towards the cyclic carbonates. MIL-101(Cr) for the cycloaddition of carbon dioxide with epoxides is demonstrated to be a robust and stable catalyst able to be re-used at least five times without loss in activity.

Microwave-Assisted Hydrothermal Synthesis of Mesoporous V-MCM-41 Materials with Good Hydrothermal Stability

2011 ◽  
Vol 233-235 ◽  
pp. 1451-1454
Author(s):  
Jun Qiang Xu ◽  
Wei Chu ◽  
Fang Guo ◽  
Xue Jun Quan
Keyword(s):  
Hydrothermal Synthesis ◽  
High Surface ◽  
High Surface Area ◽  
Mesoporous Structure ◽  
Microwave Treatment ◽  
Hydrothermal Stability ◽  
Conventional Heating ◽  
Microwave Assisted ◽  
Adsorption Analysis ◽  
Mcm 41

Mesoporous V-MCM-41 materials with good hydrothermal stability had been synthesized by microwave-assisted hydrothermal method. The samples by microwave-assisted hydrothermal synthesis and conventional heating remain the same mesoporous structure by XRD and N2adsorption analysis. The V-MCM-41 materials by microwave-assisted hydrothermal synthesis show the good hydrothermal stability, close to that of the materials by conventional heating. The high surface area of the sample by 720 W microwave treatment for 8 min was the same as that of the sample by conventional heating (110 °C for 12 h).

scholarly journals Fabrication of Ni-Based Bimodal Porous Catalyst for Dry Reforming of Methane

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1220
Author(s):  
Linghui Lyu ◽  
Yunxing Han ◽  
Qingxiang Ma ◽  
Shengene Makpal ◽  
Jian Sun ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Noble Metals ◽  
Carbon Deposition ◽  
Physical Adsorption ◽  
High Surface ◽  
High Surface Area ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Porous Catalyst ◽  
Temperature Programmed

Dry reforming of methane (DRM) can effectively convert two greenhouse gases into high-valued chemicals, in which the syngas produced by the reaction can be directly used as raw gases for Fischer–Tropsch synthesis and methanol synthesis. Ni-based catalysts for the DRM reaction with comparable initial activity to noble metals are the focus of most researchers, but their poor carbon deposition resistance easily causes their low stability. More importantly, the nickel loading will affect the catalytic activity and carbon deposition resistance of the catalyst. Herein, a series of Ni/Al2O3 catalysts with bimodal pores was prepared and characterized by X-ray diffraction (XRD), N2 physical adsorption–desorption, H2-temperature programmed reduction (H2-TPR), temperature programmed hydrogenation (TPH), Raman, and thermogravimetric analysis (TG). The results show that the interesting bimodal structure catalysts could provide a high surface area and contribute to the mass transfer. Besides, the catalytic performance of the DRM reaction is sensitive to nickel loadings. In this study, the Ni/Al2O3 catalyst with nickel loadings of 6% and 8% exhibited excellent catalytic activity and carbon deposition resistance. These findings will provide a new strategy to design a highly efficient and stable heterogeneous catalyst for industry.

Structure and composition of metal particles in Pt-Sn/Al2O3 bimetallic catalysts

1990 ◽  
Vol 48 (4) ◽  
pp. 278-279
Author(s):  
A. Sachdev ◽  
J. Schwank
Keyword(s):  
Bimetallic Catalysts ◽  
Bimetallic Catalyst ◽  
Size Structure ◽  
High Surface ◽  
High Surface Area ◽  
Metal Particles ◽  
Alloy Formation ◽  
Particle Size Range ◽  
Oxide Supports ◽  
Petroleum Fractions

Platinum - tin bimetallic catalysts have been primarily utilized in the chemical industry in the catalytic reforming of petroleum fractions. In this process the naphtha feedstock is converted to hydrocarbons with higher octane numbers and high anti-knock qualities. Most of these catalysts contain small metal particles or crystallites supported on high surface area insulating oxide supports. The determination of the structure and composition of these particles is crucial to the understanding of the catalytic behavior. In a bimetallic catalyst it is important to know how the two metals are distributed within the particle size range and in what way the addition of a second metal affects the size, structure and composition of the metal particles. An added complication in the Pt-Sn system is the possibility of alloy formation between the two elements for all atomic ratios.

scholarly journals Flower-Shaped C-Dots/Co3O4{111} Constructed with Dual-Reaction Centers for Enhancement of Fenton-Like Reaction Activity and Peroxymonosulfate Conversion to Sulfate Radical

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 135
Author(s):  
Zhibin Wen ◽  
Qianqian Zhu ◽  
Jiali Zhou ◽  
Shudi Zhao ◽  
Jinnan Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Site ◽  
High Surface ◽  
High Surface Area ◽  
Reaction Centers ◽  
Organic Radicals ◽  
The Other ◽  
High Catalytic Activity ◽  
High Adsorption ◽  
High Turnover

Novel flower-shaped C-dots/Co3O4{111} with dual-reaction centers were constructed to improve the Fenton-like reaction activity and peroxymonosulfate (PMS) conversion to sulfate radicals. Due to the exposure of a high surface area and Co3O4{111} facets, flower-shaped C-dots/Co3O4{111} could provide more Co(II) for PMS activation than traditional spherical Co3O4{110}. Meanwhile, PMS was preferred for adsorption on Co3O4{111} facets because of a high adsorption energy and thereby facilitated the electron transfer from Co(II) to PMS. More importantly, the Co–O–C linkage between C-dots and Co3O4{111} induced the formation of the dual-reaction center, which promoted the production of reactive organic radicals (R•). PMS could be directly reduced to SO4−• by R• over C-dots. On the other hand, electron transferred from R• to Co via Co–O–C linkage could accelerate the redox of Co(II)/(III), avoiding the invalid decomposition of PMS. Thus, C-dots doped on Co3O4{111} improved the PMS conversion rate to SO4−• over the single active site, resulting in high turnover numbers (TONs). In addition, TPR analysis indicated that the optimal content of C-dots doped on Co3O4{111} is 2.5%. More than 99% of antibiotics and dyes were degraded over C-dots/Co3O4{111} within 10 min. Even after six cycles, C-dots/Co3O4{111} still remained a high catalytic activity.

scholarly journals Promotional Effects of Rare-Earth Praseodymium (Pr) Modification over MCM-41 for Methyl Mercaptan Catalytic Decomposition

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 400
Author(s):  
Xiaohua Cao ◽  
Jichang Lu ◽  
Yutong Zhao ◽  
Rui Tian ◽  
Wenjun Zhang ◽  
...  
Keyword(s):  
Dimethyl Sulfide ◽  
Catalytic Decomposition ◽  
Product Distribution ◽  
Acid Sites ◽  
Methyl Mercaptan ◽  
Praseodymium Oxide ◽  
X Ray ◽  
Xps Characterization ◽  
Temperature Programmed ◽  
Mcm 41

Praseodymium (Pr)-promoted MCM-41 catalyst was investigated for the catalytic decomposition of methyl mercaptan (CH3SH). Various characterization techniques, such as X-ray diffraction (XRD), N2 adsorption–desorption, temperature-programmed desorption of ammonia (NH3-TPD) and carbon dioxide (CO2-TPD), hydrogen temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectrometer (XPS), were carried out to analyze the physicochemical properties of material. XPS characterization results showed that praseodymium was presented on the modified catalyst in the form of praseodymium oxide species, which can react with coke deposit to prolong the catalytic stability until 120 h. Meanwhile, the strong acid sites were proved to be the main active center over the 10% Pr/MCM-41 catalyst by NH3-TPD results during the catalytic elimination of methyl mercaptan. The possible reaction mechanism was proposed by analyzing the product distribution results. The final products were mainly small-molecule products, such as methane (CH4) and hydrogen sulfide (H2S). Dimethyl sulfide (CH3SCH3) was a reaction intermediate during the reaction. Therefore, this work contributes to the understanding of the reaction process of catalytic decomposition methyl mercaptan and the design of anti-carbon deposition catalysts.

scholarly journals Cobalt-Based Metal Organic Frameworks as Solids Catalysts for Oxidation Reactions

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 95
Author(s):  
Amarajothi Dhakshinamoorthy ◽  
Eva Montero Lanzuela ◽  
Sergio Navalon ◽  
Hermenegildo Garcia
Keyword(s):  
Aerobic Oxidation ◽  
High Surface ◽  
Metal Organic Frameworks ◽  
High Surface Area ◽  
Acid Sites ◽  
Crystalline Lattice ◽  
Oxidation Reactions ◽  
Solid Catalysts ◽  
Long Term Stability ◽  
Metal Organic

Metal organic frameworks (MOFs) are porous crystalline solids whose frameworks are constituted by metal ions/nodes with rigid organic linkers leading to the formation of materials having high surface area and pore volume. One of the unique features of MOFs is the presence of coordinatively unsaturated metal sites in their crystalline lattice that can act as Lewis acid sites promoting organic transformations, including aerobic oxidation reactions of various substrates such as hydrocarbons, alcohols, and sulfides. This review article summarizes the existing Co-based MOFs for oxidation reactions organized according to the nature of substrates like hydrocarbon, alcohol, olefin, and water. Both aerobic conditions and peroxide oxidants are discussed. Emphasis is placed on comparing the advantages of using MOFs as solid catalysts with respect to homogeneous salts in terms of product selectivity and long-term stability. The final section provides our view on future developments in this field.

scholarly journals Sulfamic acid pyromellitic diamide-functionalized MCM-41 as a multifunctional hybrid catalyst for melting-assisted solvent-free synthesis of bioactive 3,4-dihydropyrimidin-2-(1H)-ones

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ehsan Valiey ◽  
Mohammad G. Dekamin ◽  
Zahra Alirezvani
Keyword(s):  
Structural Characteristics ◽  
Biginelli Reaction ◽  
High Surface ◽  
High Surface Area ◽  
Sulfamic Acid ◽  
Solvent Free ◽  
Biologically Active ◽  
Green Protocol ◽  
Solvent Free Conditions ◽  
Mcm 41

AbstractThis study introduces a practical approach to fabricate a novel hybrid acidic catalyst, namely sulfamic acid pyromellitic diamide-functionalized MCM-41 (MCM-41-APS-PMDA-NHSO3H). Various techniques such as FTIR, TGA, XRD, BET, FESEM, and EDX were used to confirm its structural characteristics. The efficiency of the new MCM-41-APS-PMDA-NHSO3H organosilica nanomaterials, as a heterogenous nanocatalyst, was examined in the synthesis of biologically active 3,4-dihydropyrimidin-2-(1H)-one derivatives under solvent-free conditions. It was found that the nanoporous MCM-41-APS-PMDA-NHSO3H, demonstrating acidic nature and high surface area, can activate all the Biginelli reaction components to afford desired 3,4-dihydropyrimidin-2-(1H)-ones under solvent-free conditions in short reaction time. Furthermore, easy and quick isolation of the new introduced hybrid organosilica from the reaction mixture as well as its reusability with negligible loss of activity in at least five consecutive runs are another advantages of this green protocol.

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