Promoters and Poisons

Abstract

The sections in this article are Introduction Modifiers in Catalysis Structural Modifiers Bonding Modifiers Promoters and Poisons for Some Important Catalytic Reactions Steam Reforming A Reactive Sites on Ni Catalysts B Alkali and Alkaline Earth Promoters for Ni Catalysts C Sulfur Poisoning of Ni Catalysts Water‐Gas Shift Reaction A Iron‐Based Catalysts: High‐Temperature Shift Catalysts a Structural Modifiers in Iron‐Based Catalysts b Metal and Metal Oxides as Promoters for Catalytic Activity B Copper‐Based Catalysts: Low‐Temperature Shift Catalysts a Structural Modifiers b Cesium Modifiers c Sulfur Poisoning Methanation A Active Phase and Structural Modifiers B Electropositive Modifiers C Electronegative Modifiers F ischer– T ropsch Synthesis A Fe ‐Based Catalysts a Active Phase and Structural Modifiers b Metal Modifiers c Sulfur Modification B Co‐Based Catalysts a Electropositive Modifiers b Electronegative Modifiers Ammonia Synthesis A Summary of Iron Ammonia Synthesis Catalysts B Ruthenium Catalysts for Ammonia Synthesis a Active Phase and Structural Modifiers b Metal Modifiers c Poisoning Modifiers Case Studies of the Fundamental Basis of Modifier Action in Catalysis Ca promotion in Pd / Si O 2 Catalysts for Methanol Synthesis Direct Formation of Hydrogen Peroxide A Pd Catalysts for Direct H 2 O 2 Synthesis B Promotion Effects of Halide Anions Methane Reforming on Au  Ni Catalysts A Recent Studies on Ni Catalysts for Methane Reforming B Methane Reforming on Au ‐Modified Ni Catalysts Oxidative Dehydrogenation of Alkanes A Effects of Supports, Loading, and Preparation B Effect of Alkali Metal Additives on Vanadia Catalysts Summary

High Activity of Au/K/TiO2(110) for CO Oxidation: Alkali-Metal-Enhanced Dispersion of Au and Bonding of CO

“…A strong interaction between CO and K leads to a rupture of C–O bonds. A similar phenomenon has been observed for coadsorption of K and CO on metal surfaces, and it may reflect an intrinsic property of the alkali metal. − Part of the generated CO x could come from a direct reaction of CO with surface oxygen sites facilitated by the presence of K cations. Potassium carbonate-like species are very stable compounds .…”

“…For years, it has been known that alkali metals can act as promoters of catalytic or chemical reactions present in a large number of industrial processes (CO oxidation, Fischer–Tropsch synthesis, alcohol production from CO/CO 2 hydrogenation, water–gas shift reaction, ammonia synthesis, olefin epoxidation, NO reduction, etc. ). , Alkali metals can enhance the activity or selectivity of catalysts based on oxides, carbides, or sulfides. , The precise mechanisms behind the alkali metal promotional effects are not yet fully understood. In principle, an alkali metal can participate directly in a catalytic process, binding the reactants or products, or it can modify the chemical properties of the catalyst components through ensemble or electronic effects. − …”

“…). , Alkali metals can enhance the activity or selectivity of catalysts based on oxides, carbides, or sulfides. , The precise mechanisms behind the alkali metal promotional effects are not yet fully understood. In principle, an alkali metal can participate directly in a catalytic process, binding the reactants or products, or it can modify the chemical properties of the catalyst components through ensemble or electronic effects. − …”

Potassium and Water Coadsorption on TiO2(110): OH-Induced Anchoring of Potassium and the Generation of Single-Site Catalysts

“…Alkali metals act as promoters of heterogeneous catalysts in a very wide range of important chemical processes (ammonia synthesis, CO oxidation, NO reduction, alcohol synthesis from CO/CO 2 hydrogenation, the water–gas shift (WGS) reaction, Fischer–Tropsch synthesis, olefin epoxidation, etc.) . The precise mechanisms behind the alkali promotional effects are not yet fully understood .…”

The Mechanism of Potassium Promoter: Enhancing the Stability of Active Surfaces

“…

Owing to their outstanding effect on improving catalytic reactivity, alkali-metal promoters have been widely used in industry [1,2] and extensively studied in academia. [3][4][5][6][7][8][9][10][11][12] Potassium-promoted iron catalysts for Fischer-Tropsch synthesis (FTS) and ammonia synthesis are the most representative examples of this effect.

…”