Calculation of the kinetics of catalyst regeneration by burning coke following a temperature ramp

The effect on combustion in air of the nature of the coke deposited in HZSM5 zeolites used in the MTG process has been studied. This coke is highly hydrogenated and unstable, and its H/C ratio decreases during combustion or when a previous thermal treatment is carried out. Coke H/C ratio greatly affects its reactivity during combustion; consequently, a severe thermal equilibration treatment is recommended for reproducibility of results. Combustion kinetics of equilibrated coke, when it is released from the catalyst, has been proven to be similar to that of the coke deposited on other catalysts for several processes. Lower coke reactivity for aging and combustion, on being deposited within the HZSM5 zeolite, must be attributed to air−coke contact restrictions due to the location of the coke, which partially impedes the flow of air into the crystals.

Section: Methodsmentioning

confidence: 99%

Role of Coke Characteristics in the Regeneration of a Catalyst for the MTG Process

Ortega

Gayubo

Aguayo

et al. 1997

“…A temperature above 200 °C was found to be necessary for complete regeneration of the catalyst. To calculate the regeneration kinetics of SiO 2 –Al 2 O 3 catalysts after the isomerization of cis -butene at 240 °C, Gayubo et al used the simple approach of ramping the temperature during oxidation . They used different starting temperatures for the ramp, to compare the kinetic parameters.…”

Section: Oxidation Of Carbonaceous Depositsmentioning

confidence: 99%

“…To calculate the regeneration kinetics of SiO 2 − Al 2 O 3 catalysts after the isomerization of cis-butene at 240 °C, Gayubo et al used the simple approach of ramping the temperature during oxidation. 408 They used different starting temperatures for the ramp, to compare the kinetic parameters. The optimum starting temperature that gave values similar to the numerical solution was 400 °C.…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

Formation and Oxidation/Gasification of Carbonaceous Deposits: A Review

Mahamulkar

Yin

Agrawal

et al. 2016

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.

Section: Resultsmentioning

confidence: 99%

“…For the previous scheme the following kinetic equations are established: Equation 2, first-order with respect to each one of the reactants, coke and oxygen, is widely accepted in the literature when coke combustion is not under diffusional restrictions. [12][13][14][15][16]18,[30][31][32][33][34][35] Methodology. It consisted of fitting the experimental results of the coke content remaining in the catalyst and the flow rates of O 2 , CO, CO 2 , and H 2 O in the outlet stream, to eq 2 and to the equations of mass conserva-tion in the calorimeter (fixed bed) for O 2 , CO, CO 2 , and H 2 O.…”

Section: Kinetic Scheme It Includes the Following Reactionsmentioning

confidence: 99%

Kinetics of Gaseous Product Formation in the Coke Combustion of a Fluidized Catalytic Cracking Catalyst

Arandes

Abajo

Fernández

et al. 1999

Combustion of the coke deposited on a commercial catalytic cracking catalyst is studied by differential scanning calorimetry. The conditions of the industrial operation in a fluidized catalytic cracking unit causing deactivation (feed, contact time, and temperature, C/O ratio) and those used for regeneration (catalyst stripping and temperature) have been reproduced. Combustion heat of coke is strongly dependent on combustion temperature and on deactivation severity (reaction conditions). Kinetic equations for the formation of gaseous combustion products, CO, CO2, and H2O, have been determined, which are useful in the design of industrial regenerators.