Chemical Reactor Engineering Centre Research Articles

The CREC-GS-Optiprobes and its focal region: Gas–solid flow measurements in down flow reactors

The Chemical Reactor Engineering Center – Gas Solid – Optiprobes (CREC-GS-Optiprobe) can be used to determine particle cluster properties in down flow reactors. These properties include solid hold-up, cluster size and cluster velocity. Critical to this task is the determination of the “focal region”. It is established in this study that the CREC-GS Optiprobes display an “effective focal region” smaller than the focal region calculated using geometrical and optical considerations. In this respect, an “effective focal region” of 118 μm with a standard deviation of 34 μm is established on the basis of different considerations including experimental observations. The existence of this “effective focal region” is most valuable in downer units given it makes the CREC-Optiprobe a suitable tool for measurements of clusters sizes with an average diameter of 84 μm FCC particles as well as local solid concentration.

Nickel on lanthanum-modified γ-Al 2O 3 oxygen carrier for CLC: Reactivity and stability

This study deals with the development of a lanthanum-modified Ni/La-γ-Al 2O 3 oxygen carrier suitable for a fluidized bed chemical-looping combustion (CLC) process. BET specific surface area analysis shows that the addition of La favors the thermal stability of γ-Al 2O 3 by preventing phase transformation. Temperature programmed characterization shows that the presence of La enhances the reducibility of the oxygen carrier by influencing the metal–support interactions helping the formation of reducible nickel species. Reactive characterization of the prepared oxygen carriers in a Chemical Reactor Engineering Center (CREC) fluidized Riser Simulator, using multiple reduction/oxidation cycles, demonstrates that the Ni/La-γ-Al 2O 3 particles display excellent reactivity and stability. The addition of La in the Ni/La-γ-Al 2O 3 influences the state of the surface minimizing the formation of nickel aluminate. It is argued that the addition of La also inhibits metal particle agglomeration by maintaining consistent metal dispersion during the cyclic oxidation/reduction processes.

Kinetic Modeling of Catalytic Cracking of Gas Oil Feedstocks: Reaction and Diffusion Phenomena

Catalytic cracking experiments of vacuum gas oil on fluid catalytic cracking (FCC)-type catalysts are carried out in a fluidized bench-scale batch Chemical Reactor Engineering Centre (CREC) riser simulator reactor. These experiments are conducted under operating conditions similar to those of the industrial FCC process in terms of temperature, catalyst-to-oil ratio, partial pressure of reactant and products, and reaction times. The crystallite size of the supported zeolite is varied between 0.4 and 0.9 microns with both activity and selectivity being monitored. A five-lump kinetic model describing the catalytic cracking of vacuum gas oil is considered, which accounts for diffusional constraints experienced by hydrocarbon species while evolving in the zeolite pore network. This study provides insights into the effect of intracrystalline diffusion in the catalytic cracking of heavy feedstocks. Results show that the catalyst with the smaller crystallite size provides higher activity and selectivity for desirable intermediate products (gasoline) and lower selectivity for terminal products (coke).

Particle velocity and particle clustering in down-flow reactors

Particle clustering is a phenomenon of importance in many applications in gas–solid fluidized beds. Using a novel Chemical Reactor Engineering Centre Gas–Solid Optiprobe ( CREC-GS-Optiprobe) equipped with a Graded Refractive INdex ( GRIN) lens to form a 285 μm diameter high illuminated region at 5.4 mm away from the tip of the sensor, particle cluster lengths were measured with minimum probe intrusion interference. Experiments were developed in a 3 m height and 0.0263 m diameter acrylic unit using a pair of CREC-GS-Optiprobes spaced 6.05 mm with the probes placed at 1.85 m away from the gas injection port. Operating conditions were varied from 1 to 3 m/s gas superficial velocities and from 2 to 12 kg/m 2 s particle solid fluxes resulting in solid hold-ups between the 0.001 and 0.003 ranges. Acquired signals displayed distinctive double peaks showing unequivocally the simultaneous detection of particle clusters on both probes. It is concluded that in down-flow units (FCC particles of 70 μm) catalyst particles evolve as particle strings with a relatively large size distribution: average cluster size ranging between 2.0 and 6.3 times of the average particle diameter with most of the particles strings having between 2.9 and 5.5 times of the average particle diameter.

Catalytic Dry Reforming of Methane in a CREC Riser Simulator Kinetic Modeling and Model Discrimination

The present study deals with catalytic dry methane reforming in a fluidized Chemical Reactor Engineering Centre (CREC) riser simulator and with the modeling of the obtained results using several kinetic rate equations. Experiments were designed and developed using a statistical criterion that optimizes the effort expended for model discrimination. From the eight models originally considered, six of them were initially found to fit the data. However, only one of them was later on retained using model discrimination. Results of the study show that both the adsorption of methane and the adsorption of carbon dioxide play an important role in determining the observed rate of the methane dry reforming reaction and suggest that methane and carbon dioxide adsorb on different sites of the catalyst. The study is also valuable in providing a sound rate equation applicable in the context of a Catforming process under current development at the CREC of the University of Western Ontario.

Preface: Engineering Foundation Conference in Barga, Italy

ADVERTISEMENT RETURN TO ISSUEEditorialNEXTPreface: Engineering Foundation Conference in Barga, ItalyFranco Berruti and Hugo de LasaView Author Information Chemical Reactor Engineering Centre Faculty of Engineering Science University of Western Ontario London, Ontario N6A 5B9, CanadaCite this: Ind. Eng. Chem. Res. 2001, 40, 23, 5043Publication Date (Web):October 9, 2001Publication History Published online9 October 2001Published inissue 1 November 2001https://doi.org/10.1021/ie0107385Copyright © 2001 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views288Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (10 KB) Get e-AlertsSUBJECTS:Catalysis,Chemical engineering and industrial chemistry,Reaction engineering,Recycling Get e-Alerts