Effects of Nb Promoter on the Properties of Cu/ZnO/SBA-15 Catalyst and Performance in Methanol Production

2016 ◽  
Vol 708 ◽  
pp. 94-97 ◽  
Author(s):  
Noor Asmawati Mohd Zabidi ◽  
Sara Tasfy ◽  
Maizatul Shima Shaharun
Keyword(s):  
Mesoporous Silica ◽  
Active Sites ◽  
Fixed Bed ◽  
Alternative Route ◽  
Methanol Production ◽  
Surface Areas ◽  
Attractive Option ◽  
And Performance ◽  
Hydrogenation Of Co

Hydrogenation of CO2 provides an alternative route for methanol production and attractive option for CO2 utilization. The present work investigates the synthesis of Cu-based catalyst on mesoporous silica (SBA-15) and promotion of the Cu-based catalyst with niobium (Nb). The addition of Nb promoter enhanced the reducibility and dispersion of the active sites as well as increased the BET and Cu surface areas. The performance of the synthesized catalyst in the hydrogenation of CO2 was evaluated in a fixed-bed microreactor at 523K, 22.5bar and H2/CO2 of 3. The CO2 conversion using the Cu/ZnO/SBA-15 catalyst was 14.2 % and increased to 17.1% on the Nb-promoted catalyst. The yield of methanol obtained using the un-promoted Cu-based catalyst was 51.4 g/h.gcat and it increased to 143 g/h.gcat over the Nb-promoted catalyst.

scholarly journals Functionalized Mesoporous Silica Membranes for CO2Separation Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Hyung-Ju Kim ◽  
Hee-Chul Yang ◽  
Dong-Yong Chung ◽  
In-Hwan Yang ◽  
Yun Jung Choi ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Molecular Sieves ◽  
Three Dimensional ◽  
Molecular Transport ◽  
Advanced Materials ◽  
Silica Membranes ◽  
Surface Areas ◽  
Functionalized Mesoporous Silica ◽  
Potential Applications ◽  
And Performance

Mesoporous silica molecular sieves are emerging candidates for a number of potential applications involving adsorption and molecular transport due to their large surface areas, high pore volumes, and tunable pore sizes. Recently, several research groups have investigated the potential of functionalized mesoporous silica molecular sieves as advanced materials in separation devices, such as membranes. In particular, mesoporous silica with a two- or three-dimensional pore structure is one of the most promising types of molecular sieve materials for gas separation membranes. However, several important challenges must first be addressed regarding the successful fabrication of mesoporous silica membranes. First, a novel, high throughput process for the fabrication of continuous and defect-free mesoporous silica membranes is required. Second, functionalization of mesopores on membranes is desirable in order to impart selective properties. Finally, the separation characteristics and performance of functionalized mesoporous silica membranes must be further investigated. Herein, the synthesis, characterization, and applications of mesoporous silica membranes and functionalized mesoporous silica membranes are reviewed with a focus on CO2separation.

Treatment of leachate from the anaerobic fermentation of solid wastes using two biofilm support media

2004 ◽  
Vol 49 (11-12) ◽  
pp. 287-294 ◽  
Author(s):  
I. Comett ◽  
S. Gonzalez-Martinez ◽  
P. Wilderer
Keyword(s):  
Anaerobic Fermentation ◽  
Fixed Bed ◽  
Dry Mass ◽  
Ammonia Removal ◽  
Cod Removal ◽  
Solid Wastes ◽  
Support Materials ◽  
Surface Areas ◽  
Biofilm Support ◽  
Different Response

Biofilms growing on different carrier media have a different response to the nutrients contained in wastewater. Biofilms have proven to be an alternative to the treatment of wastewater containing higher concentrations of contaminants. The main objective of this research was to compare two biofilm support media for the treatment of leachate from the anaerobic fermentation of solid wastes. The removal of organic matter and ammonia was achieved in two fixed bed biofilm reactors containing Kaldnes® and Linpor® support materials with specific surface areas of 490 and 270 m2/m3, respectively, and operating under the sequencing batch procedure during 204 days. The Linpor reactor achieved higher total COD removal than the Kaldnes reactor (47% and 39%, respectively). Linpor was shown to be less sensitive to influent COD changes than Kaldnes. The effluent total COD values of Kaldnes were higher than Linpor. The dissolved COD removal was 21% for both reactors. The average ammonia removal for Linpor was 72% and 42% for Kaldnes. The matrix of Linpor allows higher concentrations of microorganisms (as dry mass) than Kaldnes. The dry mass concentration was related to the "active" exposed surface area of the biofilm. This is considered to be the cause for the better performance of Linpor when compared with Kaldnes.

Microwave Activation of Homogeneous and Heterogeneous Catalytic Reactions

1997 ◽  
Vol 62 (2) ◽  
pp. 347-354 ◽  
Author(s):  
Milan Hájek
Keyword(s):  
Active Sites ◽  
Specific Effect ◽  
Point Of View ◽  
Heterogeneous Reactions ◽  
Microwave Activation ◽  
Rate Enhancement ◽  
Heterogeneous Catalytic ◽  
Order Of Magnitude ◽  
And Performance ◽  
Alkylation Reactions

Microwave heating was applied in homogeneous and in heterogeneous reactions and the results were compared from the point of view of activation of chemical reactions. Reactions including the addition of halo compounds to alkenes catalyzed by copper and ruthenium complexes in different solvents and NaY zeolite catalyzed alkylation of secondary amine in the absence of solvent were studied as model reactions to compare possibilities of microwave activation of reactants and catalysts. Rate enhancement of over one order of magnitude in homogeneous reactions was caused mainly by thermal dielectric heating effect which resulted from the effective coupling of microwaves to polar solvents. Activation of reactants and catalysts was very low if any. In heterogeneously catalyzed alkylation reactions highly efficient activation of zeolite catalyst was recorded. The results indicated that the best reaction conditions were in experiments when both activation of catalyst and performance of reaction were carried out under microwave conditions. Rate enhancement was most probably caused by "hot spots" or by "selective heating" of active sites. In both homogeneous and heterogeneous reactions non-thermal activation (specific effect) was excluded.

Robust transparent mesoporous silica membranes as matrices for colorimetric sensors

RSC Advances ◽  
2015 ◽  
Vol 5 (21) ◽  
pp. 16549-16553 ◽  
Author(s):  
Donghun Kim ◽  
Bradley F. Chmelka
Keyword(s):  
Heavy Metal ◽  
Mesoporous Silica ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Colorimetric Detection ◽  
High Surface ◽  
Silica Membranes ◽  
Surface Areas ◽  
Functionalized Mesoporous Silica ◽  
Colorimetric Sensors

Transparent functionalized mesoporous silica membranes have been prepared with high surface areas (∼500 m2 g−1) that exhibit high sensitivities for colorimetric detection and sensing of dilute heavy-metal ions (e.g., Pb2+).

scholarly journals Highly Selective Au/ZnO via Colloidal Deposition for CO2 Hydrogenation to Methanol: Evidence of AuZn Role

2021 ◽  
Vol 16 (1) ◽  
pp. 44-51
Author(s):  
Hasliza Bahruji ◽  
Mshaal Almalki ◽  
Norli Abdullah
Keyword(s):  
Active Sites ◽  
Au Nanoparticles ◽  
High Selectivity ◽  
Average Diameter ◽  
Co2 Hydrogenation ◽  
Impregnation Method ◽  
Co2 Conversion ◽  
Methanol Production ◽  
Surface Oxygen Vacancy ◽  
Colloidal Method

Gold, Au nanoparticles were deposited on ZnO, Al2O3, and Ga2O3 via colloidal method in order to investigate the role of support for CO2 hydrogenation to methanol. Au/ZnO was also produced using impregnation method to investigate the effect of colloidal method to improve methanol selectivity. Au/ZnO produced via sol immobilization showed high selectivity towards methanol meanwhile impregnation method produced Au/ZnO catalyst with high selectivity towards CO. The CO2 conversion was also influenced by the amount of Au weight loading. Au nanoparticles with average diameter of 3.5 nm exhibited 4% of CO2 conversion with 72% of methanol selectivity at 250 °C and 20 bar. The formation of AuZn alloy was identified as active sites for selective CO2 hydrogenation to methanol. Segregation of Zn from ZnO to form AuZn alloy increased the number of surface oxygen vacancy for CO2 adsorption to form formate intermediates. The formate was stabilized on AuZn alloy for further hydrogenation to form methanol.  The use of Al2O3 and Ga2O3 inhibited the formation of Au alloy, and therefore reduced methanol production. Au/Al2O3 showed 77% selectivity to methane, meanwhile Au/Ga2O3 produced 100% selectivity towards CO. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

On efficiency of vanadium-oxide promoter in cobalt Fischer – Tropsch catalysts

2021 ◽  
Vol 1 (1-2) ◽  
pp. 15
Author(s):  
Elham Yaghoobpour ◽  
Yahya Zamani ◽  
Saeed Zarrinpashne ◽  
Akbar Zamaniyan
Keyword(s):  
Vanadium Oxide ◽  
Active Sites ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Bet Surface Area ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Fischer Tropsch ◽  
Co Conversion ◽  
Loading Amount

Promoters and their loading amount have crucial roles in cobalt Fischer – Tropsch catalysts. In this regard, the effects of vanadium oxide (V2O5) as a proposed promoter for Co catalyst supported on TiO2 have been investigated. Three catalysts with 0, 1, and 3 wt.% of V2O5 promoter loading are prepared by the incipient wetness impregnation method, and characterized by the BET surface area analyzer, XRD, H2-TPR, and TEM techniques. The fixed-bed reactor was employed for their evaluations. It was found that the catalyst containing 1 wt.% V2O5 has the best performance among the evaluated catalysts, demonstrating remarkable selectivity: 92 % C5+ and 5.7 % CH4, together with preserving the amount of CO conversion compared to the unpromoted catalyst. Furthermore, it is reported that the excess addition of V2O5 promoter (> 1 wt.%) in the introduced catalyst leads to the detrimental effect on the CO conversion and C5+ selectivity, mainly owing to diminished active sites by V2O5 loading.

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