Formation and Oxidation/Gasification of Carbonaceous Deposits: A Review

Abstract

A wide variety of hydrocarbon processes, catalytic or noncatalytic, involve the formation of carbon deposits, either on catalysts or on reactor (or engine/exhaust) surfaces. Therefore, researchers have developed a large array of catalysts to aid the combustion of these deposits. Recently, the mechanism of catalytic carbon oxidation and/or gasification has been the focus of research in an attempt to design better catalysts for carbon removal. With this approach, understanding the mechanism of formation of different types of carbon deposits is desired. Efforts undertaken for studying oxidation or gasification of various forms of carbon deposits are discussed in this review, along with the techniques used to study the mechanism of oxidation/gasification. The kinetics of catalyzed and noncatalytic carbon oxidation are described in detail. The effect of reactive gases such as NO x , water vapor, CO 2 , and SO 2 on the gasification behavior of carbon deposits is also discussed. Reaction rates of oxidation/gasification of carbon under different operating conditions have been calculated, allowing for a comprehensive overview of carbon removal reactivity.

Coke formation and deactivation during catalytic reforming of biomass and waste pyrolysis products: A review

“…Furthermore, X-ray photoelectron, 13 where coke is mainly present in catalysts with a low porosity [215,220]. On the other hand, 13 C NMR and IR are intended for the bulk sample structure [184,279,280], thus being more adequate for the study of coke in highly porous catalysts. However, since coke in reforming catalysts is routinely analyzed together with the catalyst on which it is deposited, 13 C NMR analysis is not recommended due to the ferromagnetic nature of some base transition metals (Fe, Ni, Co) used in reforming catalysts, and, to a lesser extent, the paramagnetic nature of noble transition metals (Pt, Pd and Rh, among others).…”

“…Combustion kinetics. Thermogravimetric analysis during coke combustion (TG-TPO, TG/MS-TPO) allows the determination of combustion kinetics required for the design of the catalyst regeneration step [280]. The most common procedure consists on the assumption of a mathematical expression describing the combustion rate, i.e.…”

Coke Formation during Propane Dehydrogenation over Ga−Rh Supported Catalytically Active Liquid Metal Solutions

“…In this study we focus on nature and quantity of coke formed during propane dehydrogenation over said SCALMS system. In detail, we use temperature programmed oxidation (TPO), which is a widely applied technique for studying the reactivity/stability of carbon species . TPO describes the defined heating of a (partially) carbonaceous sample to high temperatures in the presence of an oxidising atmosphere, mostly diluted oxygen.…”

“…In detail, we use temperature programmed oxidation (TPO), which is a widely applied technique for studying the reactivity/stability of carbon species. [9] TPO describes the defined heating of a (partially) carbonaceous sample to high temperatures in the presence of an oxidising atmosphere, mostly diluted oxygen. Further, the activation energy can be determined using various techniques making use of the temperature dependency of the rate constant according to Arrhenius' law.…”

Modelling coke formation in an industrial ethane‐cracking furnace for ethylene production

“…Coke formation is a complex phenomenon. The major mechanisms for coke formation are catalytic (also referred to as heterogeneous catalytic), pyrolytic (also referred to as heterogeneous non‐catalytic), and condensation (also referred to as homogeneous non‐catalytic). Catalytic coke is formed by a series of reactions catalyzed by nickel and iron present on the surface of the coils .…”