Heterogeneous Catalysis on a Disordered Surface

We introduce a simple model of heterogeneous catalysis on a disordered surface which consists of two types of randomly distributed sites with different adsorption rates. Disorder can create a reactive steady state in situations where the same model on a homogeneous surface exhibits trivial kinetics with no steady state. A rich variety of kinetic behaviors occur for the adsorbate concentrations and catalytic reaction rate as a function of model parameters.Comment: 4 pages, gzipped PostScript fil

Heterogeneous Catalysis

A heterogeneous catalyst is a functional material that continually creates active sites with its reactants under reaction conditions. These sites change the rates of chemical reactions of the reactants localized on them without changing the thermodynamic equilibrium between the materials

Improvement of Synergetic Effect In Heterogeneous Catalysis By Addition Of Metal Oxides

Over the past few years, synergetic effect has great importance in the heterogeneous catalysis structure. Synergetic effect provides the importance of the activity and stability of catalysis to produce desired product by improving the defects in the solid heterogeneous catalysis. These defects occur due to imperfection of the solid crystal lattices. And these defects can be improved by the addition of various metal oxides, which finally improve the synergetic effect or the defects in the heterogeneous catalysis. The metal oxide additives were found to influence the catalytic activity in the reaction, surface composition of the catalyst and the stability of catalysts during their operation. This paper reviews and assesses the effectiveness of different metal oxides additives in the heterogeneous catalysis activity and stability i.e. by improving synergetic effect in the heterogeneous catalysis. Keywords: synergy effect, encapsulation, mimic enzyme, BET,  coprecipitation, calcination.

Inverse opal ceria–zirconia: architectural engineering for heterogeneous catalysis

The application of inverse opal structured materials is extended to the ceria–zirconia (Ce_(0.5)Zr_(0.5)O_2) system and the significance of material architecture on heterogeneous catalysis, specifically, chemical oxidation, is examined

Heterogeneous gold catalysis

Catalysis is at the heart of many manufacturing processes and underpins provision of the goods and infrastructure necessary for the effective wellbeing of society; catalysis continues to play a key role in the manufacture of chemical intermediates and final products. There is a continuing need to design new effective catalysts especially with the drive toward using sustainable resources. The identification that gold is an exceptionally effective catalyst has paved the way for a new class of active heterogeneous and homogeneous catalysts for a broad range of reactions. As a heterogeneous catalyst gold is the most active catalyst for the oxidation of carbon monoxide at ambient temperature. It is also the most effective catalyst for the synthesis of vinyl chloride by acetylene hydrochlorination, and a gold catalyst has recently been commercialized in China for this reaction. In this outlook the nature of the active gold species for these two reactions will be explored

Active sites engineering of metal-organic frameworks for heterogeneous catalysis

With the depletion of fossil fuels and global energy crisis confronting us, there is a pressing need for developing economically, environmentally benign and efficient processes in catalytic reactions for chemical synthesis. In comparison to homogeneous catalysis, which is hurdled by metal contamination and limited recyclability, heterogeneous catalysis, which holds multiple advantages of facile separation, recyclability and potential in continues flow reaction systems, is promptly developing field in chemical manufacturing nowadays. Since the first catalytic applications of MOFs reported by Fujita and coworkers in 1994, the use of MOFs in heterogeneous catalysis is under intense investigation. From viewpoint of catalysis, the high design versatility of MOFs renders unparalleled advantages for their applications in catalysis, since it is feasible to rationally engineer not only the active sites but also its chemical environment at the atomic level. Furthermore, the ultrahigh surface area/porosity and periodical structures of MOFs is beneficial to the transportation of reactants/products and guarantee the accessibility of active sites, leading to high activity in catalysis. In principle, the catalytic sites in MOFs can be divided by several categories. 1) The organic linker and the inorganic nodes, which can be induced by direct synthesis or post-synthetic modification; 2) The inner pores of the MOFs can serve as scaffold in which the catalytic species (e.g., metal or metal oxide nanoparticle, metal complex, etc.) is encapsulated;3) The pyrolysis of MOFs to porous carbon or metal/carbon hybrid composites is prone to preserve the merits of MOFs and demonstrate huge potential in heterogeneous and electrochemical catalysis In this dissertation, I present several design of heterogeneous catalysts for desired/model catalytic reactions via active sites engineering in MOFs, that is, using MOFs as scaffold for noble metal NPs and heterogenization of organometallic species and explore its application in catalytic organic transformations; using MOFs as sacrificial templates to prepare monodisperse thiolated Pd NCs or to afford porous carbons with Lewis base sites and investigate its catalytic performance in heterogeneous catalysis. By virtue of MOFs’ tunability, versatility, and flexibility, the rationally-designed MOF catalysts exhibited excellent catalytic performance in tandem catalysis and established a clear structure-activity relationship in the heterogeneous catalysis. Future work on exploring novel and efficient tandem catalysis and elucidate the underlying mechanism of linker engineering in heterogeneous MOFs catalysis in currently undergoing

Quasi-Stationary Distributions for Models of Heterogeneous Catalysis

We construct the quasi-stationary (QS) distribution for two models of heterogeneous catalysis having two absorbing states: the ZGB model for the oxidation of CO, and a version with noninstantaneous reactions. Using a mean-field-like approximation, we study the quasi-stationary surface coverages, moment ratios and the lifetime of the QS state. We also derive an improved, consistent one-site mean-field theory for the ZGB model.Comment: 18 pages, 13 figure

Development of covalent triazine frameworks as heterogeneous catalytic supports

Covalent triazine frameworks (CTFs) are established as an emerging class of porous organic polymers with remarkable features such as large surface area and permanent porosity, high thermal and chemical stability, and convenient functionalization that promotes great potential in heterogeneous catalysis. In this article, we systematically present the structural design of CTFs as a versatile scaffold to develop heterogeneous catalysts for a variety of chemical reactions. We mainly focus on the functionalization of CTFs, including their use for incorporating and stabilization of nanoparticles and immobilization of molecular complexes onto the frameworks