Nitrogen Chemistry and Coke Transformation of FCC Coked Catalyst during the Regeneration Process

Abstract

Regeneration of the coked catalyst is an important process of fluid catalytic cracking (FCC) in petroleum refining, however, this process will emit environmentally harmful gases such as nitrogen and carbon oxides. Transformation of N and C containing compounds in industrial FCC coke under thermal decomposition was investigated via TPD and TPO to examine the evolved gaseous species and TGA, NMR and XPS to analyse the residual coke fraction. Two distinct regions of gas evolution are observed during TPD for the first time, and they arise from decomposition of aliphatic carbons and aromatic carbons. Three types of N species, pyrrolic N, pyridinic N and quaternary N are identified in the FCC coke, the former one is unstable and tends to be decomposed into pyridinic and quaternary N. Mechanisms of NO, CO and CO2 evolution during TPD are proposed and lattice oxygen is suggested to be an important oxygen resource. Regeneration process indicates that coke-C tends to preferentially oxidise compared with coke-N. Hence, new technology for promoting nitrogen-containing compounds conversion will benefit the in-situ reduction of NO by CO during FCC regeneration.

Selective Glucose Isomerization to Fructose via a Nitrogen-doped Solid Base Catalyst Derived from Spent Coffee Grounds

“…A small reflection point at °C in the DTG curve could result from the decomposition of insignificant amount of carboxyl-related groups, while rapid degradation rates that occurred from 560 to 740 °C were likely due to the decomposition of oxygen-containing groups such as ketones and lactones, and nitrogen-related species such as lactame-and pyrrole-like compounds, as suggested by a temperature-programmed desorption study equipped with mass spectrometer 38 . In addition, the mass decay evolving at the latter stage of >750 °C could be primarily associated with the decomposition of pyridinic N, which is more stable than pyrrolic N 52 . The thermal degradation analysis was in line with the results of XPS analysis and showed high thermal stability of N-enriched biochar catalyst.…”

Photocatalytic degradation of methylene blue with spent FCC catalyst loaded with ferric oxide and titanium dioxide

“…In the oil refinery, the fluid catalytic cracking (FCC) is an important secondary conversion procrss [1][2][3][4] . The crude oil can be converted into the valuable small molecules products, which is an essential process for gasoline production 5 .…”

Hydrogenation of Citral to Citronellal Catalyzed by Waste Fluid Catalytic Cracking Catalyst Supported Nickel

“…Moreover, the weak absorption peak at 1631 cm –1 is the bending vibration peak of the zeolite adsorbing water–OH. In the infrared spectrum of the wFCC sample, the weak absorption peak at 1385 cm –1 is considered to be the −N=C=O phase in-plane stretching vibration because the coke produced in the FCC process is derived from the aromatic hydrocarbons and N-containing materials in the cracking raw materials . The absorption peak of NiO/wFCC and Ni/wFCC samples loaded with Ni at 1385 cm –1 is enhanced because of the presence of nitrate, which is a common phenomenon when the supported Ni catalyst is prepared by the equal volume impregnation method.…”

“…In the infrared spectrum of the wFCC sample, the weak absorption peak at 1385 cm −1 is considered to be the −N=C=O phase in-plane stretching vibration because the coke produced in the FCC process is derived from the aromatic hydrocarbons and N-containing materials in the cracking raw materials. 19 The absorption peak of NiO/wFCC and Ni/wFCC samples loaded with Ni at 1385 cm −1 is enhanced because of the presence of nitrate, which is a common phenomenon when the supported Ni catalyst is prepared by the equal volume impregnation method. The broad absorption peak near 3453 cm −1 is caused by the stretching vibration of the zeolite adsorbing molecular water and hydroxyl OH.…”