Catalysts Supported by Porous Ceramic Layers on Ceramic or Metallic Substrates

1996 ◽  
Vol 454 ◽  
Author(s):  
John W. Geus ◽  
J. Van Giezen
Keyword(s):  
Gas Phase ◽  
Porous Ceramic ◽  
Metallic Surfaces ◽  
Gas Phase Reactions ◽  
Catalytic Reactors ◽  
Efficient Procedure ◽  
Metallic Substrates ◽  
Porous Layers ◽  
Sintered Metal ◽  
Highly Porous

ABSTRACTAfter mentioning the need for integration of the catalyst and the catalytic reactor, it is argued that thin (thickness up to about 50 μm) porous layers applied on ceramic or metallic surfaces are presenting interesting possibilities for the development of new catalytic reactors. The first type of reactions that can benefit from the new reactors are liquid-phase reactions catalyzed by a solid. Especially the selectivity of the reactions can be significantly improved. The second type of reactions are gas-phase reactions with a large thermal effect. It is argued that the rate of transport of thermal energy can be greatly improved by using sintered metal bodies within the reactor coated with highly porous ceramic layers. Finally utilization of thin ceramic porous layers in separations combined with catalytic reactions is shortly dealt with.A very efficient procedure for application of the porous ceramic layers is presented, viz., pyro-lysis of thin layer of silicone rubber or analogous compounds. Addition of, e.g., aluminum or titanium ions can be used to control the thermostability and the pore-size distribution of the layers resulting after combustion of the organic constituents.

Selective oxidations in micro-structured catalytic reactors—For gas-phase reactions and specifically for fuel processing for fuel cells

2007 ◽  
Vol 120 (1) ◽  
pp. 2-20 ◽  
Author(s):  
G. Kolb ◽  
V. Hessel ◽  
V. Cominos ◽  
C. Hofmann ◽  
H. Löwe ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Gas Phase ◽  
Gas Phase Reactions ◽  
Catalytic Reactors ◽  
Fuel Processing

scholarly journals Escaping undesired gas-phase chemistry: Microwave-driven selectivity enhancement in heterogeneous catalytic reactors

2019 ◽  
Vol 5 (3) ◽  
pp. eaau9000 ◽  
Author(s):  
A. Ramirez ◽  
J. L. Hueso ◽  
M. Abian ◽  
M. U. Alzueta ◽  
R. Mallada ◽  
...  
Keyword(s):  
Gas Phase ◽  
Solid Phase ◽  
Catalyst Support ◽  
Accurate Estimation ◽  
Gas Phase Reactions ◽  
Catalytic Reactors ◽  
Heterogeneous Catalytic ◽  
Catalyst Composition ◽  
Heterogeneous Catalytic Processes ◽  
Phase Chemistry

Research in solid-gas heterogeneous catalytic processes is typically aimed toward optimization of catalyst composition to achieve a higher conversion and, especially, a higher selectivity. However, even with the most selective catalysts, an upper limit is found: Above a certain temperature, gas-phase reactions become important and their effects cannot be neglected. Here, we apply a microwave field to a catalyst-support ensemble capable of direct microwave heating (MWH). We have taken extra precautions to ensure that (i) the solid phase is free from significant hot spots and (ii) an accurate estimation of both solid and gas temperatures is obtained. MWH allows operating with a catalyst that is significantly hotter than the surrounding gas, achieving a high conversion on the catalyst while reducing undesired homogeneous reactions. We demonstrate the concept with the CO2-mediated oxidative dehydrogenation of isobutane, but it can be applied to any system with significant undesired homogeneous contributions.

Perspective Biomass Carrier for Anaerobic Processing Systems of Organic Waste AIC

2020 ◽  
Vol 67 (1) ◽  
pp. 148-155
Author(s):  
Anatoliy V. Fedotov ◽  
Viktor S. Grigoriev ◽  
Dmitriy A. Kovalev ◽  
Andrey A. Kovalev
Keyword(s):  
Wastewater Treatment ◽  
Anaerobic Digestion ◽  
Specific Surface ◽  
Organic Waste ◽  
Porous Ceramic ◽  
Experimental Studies ◽  
Ceramic Materials ◽  
Porous Ceramics ◽  
Developed Surface ◽  
Highly Porous

To speed up the wastewater treatment under aerobic conditions and to optimize the processes of anaerobic wastewater treatment in digesters, immobilization technologies of microorganisms and enzymes on solid carriers are used. Ceramic carriers based on aluminosilicates and alumina are one of the promising inorganic biomass carriers. (Research purpose) To study the structure of porous ceramic biomass carriers for anaerobic processing of organic waste and evaluate the prospects for their use. (Materials and methods) The substrate for anaerobic digestion was a mixture of sediments of the primary and secondary sewage sumps of the Lyubertsy treatment facilities. K-65 cattle feed was used to ensure the constancy of the composition of organic substances in substrates as a cosubstrate. The authors used the method of low-temperature nitrogen adsorption of Bruner-Emmett-Teller to study the pore structure and specific surface of solid carriers on a specific surface analyzer Quntachrome Autosorb-1. (Results and discussion) The main characteristics (specific surface, volume of micro- and mesopores, predominant pore radius, water absorption and others) of chamotte foam lightweight and highly porous corundum ceramics were determined. It was revealed that ceramic materials with a developed surface and electrically conductive material provided an increase in biogas yield by 3.8-3.9 percent with an increase in methane content by an average of 5 percent. (Conclusions) The results of anaerobic digestion showed a positive effect of both a conductive carrier and highly porous ceramic materials on the process of anaerobic bioconversion of organic waste into biogas. It is advisable to expand experimental studies on the use of a conductive carrier with a developed surface based on highly porous ceramics.

Gas-Phase Reactions

1981 ◽  
Author(s):  
Victor N. Kondratiev ◽  
Evgeniĭ E. Nikitin
Keyword(s):  
Gas Phase ◽  
Gas Phase Reactions

Influence of Gas Mixing and Heating on Gas-Phase Reactions in GaN MOCVD Growth

2012 ◽  
Vol 1 (1) ◽  
pp. P46-P53 ◽  
Author(s):  
Ran Zuo ◽  
Haiqun Yu ◽  
Nan Xu ◽  
Xiaokun He
Keyword(s):  
Gas Phase ◽  
Gas Mixing ◽  
Gas Phase Reactions ◽  
Mocvd Growth

Gas Phase Reactions Activated by Nuclear Processes

1957 ◽  
Vol 79 (17) ◽  
pp. 4609-4616 ◽  
Author(s):  
Adon A. Gordus ◽  
John E. Willard
Keyword(s):  
Gas Phase ◽  
Gas Phase Reactions ◽  
Nuclear Processes

Nanocomposite ceramic powder production by laser-induced gas-phase reactions

1993 ◽  
Vol 168 (2) ◽  
pp. 177-181 ◽  
Author(s):  
E Borsella ◽  
S Botti ◽  
R Alexandrescu ◽  
I Morjan ◽  
T Dikonimos-Makris ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ceramic Powder ◽  
Gas Phase Reactions ◽  
Powder Production

Methylene. III. Gas phase reactions with 1-chloropropane

1969 ◽  
Vol 312 (1509) ◽  
pp. 141-161 ◽  
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Hydrogen Abstraction ◽  
The Other ◽  
Gas Phase Reactions ◽  
Other Hand ◽  
Chlorine Substituent ◽  
High Degree ◽  
Singlet Methylene

The work described in this and the following paper is a continuation of that in parts I and II, devoted to elucidation of the mechanism of the reactions of methylene with chloroalkanes, with particular reference to the reactivities of singlet and triplet methylene in abstraction and insertion processes. The products of the reaction between methylene, prepared by the photolysis of ketene, and 1-chloropropane have been identified and estimated and their dependence on reactant pressures, photolysing wavelength and presence of foreign gases (oxygen and carbon mon­oxide) has been investigated. Both insertion and abstraction mechanisms contribute significantly to the over-all reaction, insertion being relatively much more important than with chloroethane. This type of process appears to be confined to singlet methylene. If, as seems likely, there is no insertion into C—Cl bonds under our conditions (see part IV), insertion into C2—H and C3—H bonds occurs in statistical ratio, approximately. On the other hand, the chlorine substituent reduces the probability of insertion into C—H bonds in its vicinity. As in the chloroethane system, both species of methylene show a high degree of selectivity in their abstraction reactions. We find that k S Cl / k S H >7.7, k T Cl / k T H < 0.14, where the k ’s are rate constants for abstraction, and the super- and subscripts indicate the species of methylene and the type of atom abstracted, respectively. Triplet methylene is discriminating in hydrogen abstraction from 1-C 3 H 7 Cl, the overall rates for atoms attached to C1, C2, C3 being in the ratios 2.63:1:0.

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