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A special issue of Reactions (ISSN 2624-781X).

Deadline for manuscript submissions: closed (31 March 2022) | Viewed by 53254

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Special Issue Editors

Dr. Wenping Ma

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Guest Editor

Center for Applied Energy Research, University of Kentucky, 2540 Research Park Drive, Lexington, KY 40511, USA
Interests: heterogeneous catalysis; hydrogenation of CO or CO₂ to fuels and chemicals (Fischer-Tropsch synthesis); H₂ production; hydrocracking; process simulation
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Ajay K. Dalai

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Guest Editor

Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9, Canada
Interests: catalysts for fischer-tropsch reactions; bioenergy and biochemicals; pyrolysis; gasification; super-critical extraction; activated carbon; nanomaterials; materials synthesis; materials characterization; pollution control
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

As the global energy structure is transitioning to a lower-carbon energy system, the utilization of various regulated carbonaceous materials (X) such as coal, natural gas, biomass, biogas, organic wastes, and CO₂ in fuels and chemicals urgently require cleaner technologies. Fischer–Tropsch synthesis (FTS), water–gas shift reaction (WGS), reforming reaction, etc. are catalytic processes to convert X to ultra-clean liquid or hydrogen fuels (XTF) and various chemicals (XTC), and continuously attract significant interest worldwide because these technologies provide the scientific basis to meet substantially increased energy demands—particularly in the nations which possess low oil reserve but with rich coal, natural gas, or biomass resources, and/or fewer energy options. Simultaneously, the rapid development of renewable energy (primarily solar, wind, and hydropower) would significantly lower the cost of X gasification to syngas by utilizing multiple technologies, which helps the XTF/XTC technology be more competitive relative to the traditional oil route.

The FTS plus wax upgrading, WGS and wet/dry reforming reactions, as the heart of the XTF/XTC process, produce various types of fuels and chemicals including gasoline, diesel, kerosene, jet fuel, lubricants, waxes, methanol, ethanol, higher alcohols, and hydrogen. The catalysts (Fe, Co, Ru, Ni, Mo, Cu, Pt, zeolites, etc.), chemical reactors, and process conditions play key roles in obtaining the target products. Despite the vast number of basic studies on XTF/XTC, many issues related to the catalyst structure-performances, pretreatment effects, reaction mechanisms, kinetics, and product upgrading still remain unsolved. This Special Issue focuses on recent advances in experimental and theoretical research in XTF/XTC catalysts, catalysis, and chemical reactor technology, including (i) the development of improved catalysts or novel reactor technologies for directly making gasoline, diesel fuels, or chemicals from syngas or hydrogen fuel from steam gas, methane, and oxygenates; (ii) experimental or theoretical studies on catalyst structural characteristics and catalytic performance, reaction mechanisms, and kinetics; (iii) upgrading FTS wax to liquid fuels; and (iv) techno-economic analysis and life-cycle analysis related to XTF/XTC.

You may choose our Joint Special Issue in Crystals.

Dr. Wenping Ma
Prof. Dr. Ajay K. Dalai
Guest Editors

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Reactions is an international peer-reviewed open access quarterly journal published by MDPI.

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Keywords

Carbonaceous materials
Catalytic conversion
Catalysis
Novel catalyst studies
Novel reactor studies
Liquid fuel synthesis
Oxygenate synthesis
Hydrogen fuel
Techno-economic studies
Life-cycle analysis

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Published Papers (14 papers)

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Editorial

Jump to: Research, Review

4 pages, 172 KiB

Open AccessEditorial

Special Issue Editorial: Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals

by Wenping Ma and Ajay K. Dalai

Reactions 2022, 3(3), 329-332; https://doi.org/10.3390/reactions3030024 - 27 Jun 2022

Viewed by 1481

Abstract

Conversion of syngas or CO₂ greenhouse gas derived from various carbon-containing materials including coal, natural gas, biomass, waste plastics and biogas, or power plant, and petroleum is paramount to ensure global energy security, and recycle carbon in the earth and atmosphere and [...] Read more.

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

Research

Jump to: Editorial, Review

17 pages, 3269 KiB

Open AccessArticle

Valorization of Microcrystalline Cellulose Using Heterogeneous Protonated Zeolite Catalyst: An Experimental and Kinetics Approach

by Samuel Kassaye, Dinesh Gupta, Kamal Kishore Pant and Sapna Jain

Reactions 2022, 3(2), 283-299; https://doi.org/10.3390/reactions3020021 - 30 May 2022

Cited by 2 | Viewed by 2201

Abstract

This study aimed to valorize microcrystalline cellulose (MCC) using protonated zeolite catalysts such as (H-ZSM-5) and Cr/H-ZSM-5 (5%) in ionic liquid. The catalytic effect in synergy with 1-butyl-3-methylimidazolium Chloride ([BMIM] Cl) ionic liquid was studied in detail. The total reducing sugar (TRS) was determined using the 3, 5-dinitrisalcylic acid (DNS) array method. The catalysts were characterized using techniques such as Fourier transform infrared (FT-IR), X-ray diffraction analysis (XRD), temperature-programmed desorption of ammonia (NH₃-TPD), and BET-surface area analyzer. H-ZSM-5 effectively depolymerized cellulose with a maximum yield of 70% total reducing sugar (34% glucose, 8% fructose, and 4.5% 5-HMF). Cr/H-ZSM-5 catalyst dehydrated fructose to 5-HMF with a yield of 53%. The use of ionic liquid significantly reduced the activation energy of formation and decomposition. The activation energy determined in cellulose hydrolysis was 85.83 KJ mol⁻¹ for a reaction time of 180 min while the decomposition energy was found to be 42.5 kJ mol⁻¹. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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16 pages, 4678 KiB

Open AccessArticle

Oxidative Desulfurization of Tire Pyrolysis Oil over Molybdenum Heteropolyacid Loaded Mesoporous Catalysts

by Jasmine Kaur, Sundaramurthy Vedachalam, Philip Boahene and Ajay K. Dalai

Reactions 2021, 2(4), 457-472; https://doi.org/10.3390/reactions2040029 - 4 Nov 2021

Cited by 4 | Viewed by 3779

Abstract

Pyrolysis oil derived from waste tires consists of sulfur content in the range of 7000 to 9000 ppm. For use in diesel engines, its sulfur content must be lowered to 10 to 15 ppm. Though conventional hydrodesulfurization is suitable for the removal of sulfur from tire pyrolysis oil, its high cost provides an avenue for alternative desulfurization technologies to be explored. In this study, oxidative desulfurization (ODS), a low-cost technology, was explored for the desulfurization of tire pyrolysis oil. Two categories of titanium-incorporated mesoporous supports with 20 wt% loaded heteropoly molybdic acid catalyst (HPMo/Ti-Al₂O₃ and HPMo/Ti-TUD-1) were developed and tested for ODS of tire pyrolysis oil at mild process conditions. Catalysts were characterized by X-ray diffraction, BET-N₂ physisorption, and X-ray photoelectron spectroscopy (XPS). The incorporation of Ti into Al₂O₃ and TUD-1 frameworks was confirmed by XPS. The surface acidity of catalysts was studied by the temperature-programmed desorption of NH₃ and pyridine FTIR analyses. HPMo/Ti-Al₂O₃ and HPMo/Ti-TUD-1 catalysts contained both Lewis and Brønsted acid sites. The presence of titanium in catalysts was found to promote the ODS activity of phosphomolybdic acid. The Ti-TUD-1-supported catalysts performed better than the Ti-Al₂O₃-supported catalysts for the ODS of tire pyrolysis oil. Hydrogen peroxide and cumene peroxide were found to be better oxidants than tert-butyl hydroperoxide for oxidizing sulfur compounds of tire pyrolysis oil. Process parameter optimization by the design of experiments was conducted with an optimal catalyst along with the catalyst regeneration study. An ANOVA statistical analysis demonstrated that the oxidant/sulfur and catalyst/oil ratios were more significant than the reaction temperature for the ODS of tire pyrolysis oil. It followed the pseudo-first-order kinetics over HPMo/Ti-TUD-1. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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19 pages, 4887 KiB

Open AccessArticle

Fischer–Tropsch Synthesis: Effect of the Promoter’s Ionic Charge and Valence Level Energy on Activity

by Mirtha Z. Leguizamón León Ribeiro, Joice C. Souza, Muthu Kumaran Gnanamani, Michela Martinelli, Gabriel F. Upton, Gary Jacobs and Mauro C. Ribeiro

Reactions 2021, 2(4), 408-426; https://doi.org/10.3390/reactions2040026 - 10 Oct 2021

Cited by 4 | Viewed by 3180

Abstract

In this contribution, we examine the effect of the promoter´s ionic charge and valence orbital energy on the catalytic activity of Fe-based catalysts, based on in situ synchrotron X-ray powder diffraction (SXRPD), temperature-programmed-based techniques (TPR, TPD, CO-TP carburization), and Fischer–Tropsch synthesis catalytic testing studies. We compared the promoting effects of K (a known promoter for longer-chained products) with Ba, which has a similar ionic radius but has double the ionic charge. Despite being partially “buried” in a crystalline BaCO₃ phase, the carburization of the Ba-promoted catalyst was more effective than that of K; this was primarily due to its higher (2+) ionic charge. With Ba²⁺, higher selectivity to methane and lighter products were obtained compared to the K-promoted catalysts; this is likely due to Ba´s lesser capability of suppressing H adsorption on the catalyst surface. An explanation is provided in terms of a more limited mixing between electron-filled Ba²⁺ 5p and partially filled Fe 3d orbitals, which are expected to be important for the chemical promotion, as they are further apart in energy compared to the K⁺ 3p and Fe 3d orbitals. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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17 pages, 3337 KiB

Open AccessArticle

Hydrocracking of Octacosane and Cobalt Fischer–Tropsch Wax over Nonsulfided NiMo and Pt-Based Catalysts

by Wenping Ma, Jungshik Kang, Gary Jacobs, Shelley D. Hopps and Burtron H. Davis

Reactions 2021, 2(4), 374-390; https://doi.org/10.3390/reactions2040024 - 30 Sep 2021

Cited by 3 | Viewed by 2994

Abstract

The effect of activation environment (N₂, H₂ and H₂S/H₂) on the hydrocracking performance of a NiMo/Al catalyst was studied at 380 °C and 3.5 MPa using octacosane (C₂₈). The catalyst physical structure and acidity were characterized by BET, XRD, SEM-EDX and FTIR techniques. The N₂ activation generated more active nonsulfided NiMo/Al catalyst relative to the H₂ or H₂S activation (X_C28, 70–80% versus 6–10%). For a comparison, a NiMo/Si-Al catalyst was also tested after normal H₂ activation and showed higher activity at the same process conditions (X_C28, 81–99%). The high activity of the NiMo/Al (N₂ activation) and NiMo/Si-Al catalysts was mainly ascribed to a higher number of Brønsted acid sites (BAS) on the catalysts. The hydrocracking of cobalt wax using Pt/Si-Al and Pt/Al catalysts confirmed the superior activity of the Si-Al support. A double-peak product distribution occurred at C₄–C₆ and C₁₀–C₁₆ on all catalysts, which illustrates secondary hydrocracking and faster hydrocracking at the middle of the chain. The nonsulfided NiMo/Al and Pt/Al catalysts, and NiMo/Si-Al catalyst produced predominantly diesel (sel. 50–70%) and gasoline range (sel. > 50%) hydrocarbons, respectively, accompanied by some CH₄ and light hydrocarbons C₂–C₄. On the other hand, the hydrocarbon distribution of the Pt/Si-Al varied with conditions (i.e., diesel sel. 87–90% below 290 °C or gasoline sel. 60–70% above 290 °C accompanied by little CH₄) The dependence of the isomer/paraffin ratio on chain length was studied as well. The peak iso/paraffin value was observed at C₁₀–C₁₃ for the SiAl catalyst. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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9 pages, 2113 KiB

Open AccessArticle

The Impact of Operating Parameters on the Gas-Phase Sulfur Concentration after High Temperature Sulfur Sorption on a Supported Mo-Mn Sorbent

by Jianyu Ma, Mehdi Mahmoodinia, Kumar R. Rout and Edd A. Blekkan

Reactions 2021, 2(4), 365-373; https://doi.org/10.3390/reactions2040023 - 23 Sep 2021

Cited by 1 | Viewed by 2273

Abstract

The impact of operating parameters on H₂S capture from a syngas mixture by a Mo-promoted Mn-based high-temperature sorbent was investigated. The parameters investigated included temperature, space velocity, H₂S concentration in the feed gas, and steam content. The H₂S and SO₂ concentrations in the gas after passing over a bed of the sorbent were analyzed and compared with thermodynamic calculations. The results confirmed that low temperature, low space velocity, low H₂S concentration, and a dry feed were favorable for achieving a low residual concentration of sulfur compounds in the effluent gas. The sorbent was able to reduce the residual H₂S concentration to below 1 ppm under all tested conditions. However, the unavoidable steam content in the gas phase had a significant adverse effect on sulfur removal from the gas. An empirical model, containing the three variables, i.e., temperature, space velocity, and H₂S concentration in the feed, was developed and can be used to predict the effluent H₂S residual concentration after treatment by the 15Mn8Mo sorbent. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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14 pages, 3497 KiB

Open AccessArticle

Chain Propagation Mechanism of Fischer–Tropsch Synthesis: Experimental Evidence by Aldehyde, Alcohol and Alkene Addition

by Liping Zhou, Junhu Gao, Xu Hao, Yong Yang and Yongwang Li

Reactions 2021, 2(2), 161-174; https://doi.org/10.3390/reactions2020012 - 8 Jun 2021

Cited by 11 | Viewed by 4640

Abstract

Fischer–Tropsch synthesis (FTS) produces hundreds of hydrocarbons and oxygenates by simple reactants (CO + H₂) and the detailed chain propagation mechanism is still in dispute. An industrial iron-based catalyst was used to further clarify the mechanism by adding aldehyde, alcohol and alkene species into a fixed-bed tubular reactor. The added species were investigated in H₂ and syngas atmospheres, respectively. 1-alkene in the H₂ atmosphere presented an obvious hydrogenolysis, in which the produced C₁ species participated in C–C bond formation simultaneously. Co-feeding C_n alkene with syngas showed remarkable C_n+1 alcohol selectivity compared to the normal FTS reaction. In addition, the carbonyl group of aldehyde was extremely unstable over the iron-based catalyst and could easily be hydrogenated to an alcohol hydroxyl group, which could even undergo dehydration for hydrocarbon species formation. Experimental data confirmed that both heavier alkenes and alcohols added can be converted to chain growth intermediates and then undergo monomer insertion for chain propagation. These results provide strong evidence that the chain propagation in the FTS reaction is simultaneously controlled by the surface carbide mechanism and the CO insertion mechanism, with surface CH_x species and CO as monomers, respectively. The study is of guiding significance for FTS mechanism understanding and kinetic modeling. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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32 pages, 8165 KiB

Open AccessArticle

Fischer-Tropsch Synthesis: The Characterization and Testing of Pt-Co/SiO₂ Catalysts Prepared with Alternative Cobalt Precursors

by Mohammad Mehrbod, Michela Martinelli, Caleb D. Watson, Donald C. Cronauer, A. Jeremy Kropf and Gary Jacobs

Reactions 2021, 2(2), 129-160; https://doi.org/10.3390/reactions2020011 - 1 Jun 2021

Cited by 4 | Viewed by 3678

Abstract

Different low-cost cobalt precursors (acetate, chloride) and thermal treatments (air calcination/H₂ reduction versus direct H₂-activation) were investigated to alter the interaction between cobalt and silica. H₂-activated catalysts prepared from cobalt chloride had large Co⁰ particles (XRD, chemisorption) formed by weak interactions between cobalt chloride and silica (temperature programmed reduction (TPR), TPR with mass spectrometry (TPR-MS), TPR with extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge spectroscopy (XANES) techniques) and retained Cl-blocked active sites, resulting in poor activity. In contrast, unpromoted Co/SiO₂ catalysts derived from cobalt acetate had strong interactions between Co species and silica (TPR/TPR-MS, TPR-EXAFS/XANES); adding Pt increased the extent of the Co reduction. For these Pt-promoted catalysts, the reduction of uncalcined catalysts was faster, resulting in larger Co⁰ clusters (19.5 nm) in comparison with the air-calcined/H₂-activated catalyst (7.8 nm). Both catalysts had CO conversions 25% higher than that of the Pt-promoted catalyst prepared in the traditional manner (air calcination/H₂ reduction using cobalt nitrate) and three times higher than that of the traditional unpromoted Co/silica catalyst. The retention of residual cobalt carbide (observed in XANES) from cobalt acetate decomposition impacted performance, resulting in a higher C₁–C₄ selectivity (32.2% for air-calcined and 38.7% for uncalcined) than that of traditional catalysts (17.5–18.6%). The residual carbide also lowered the α-value and olefin/paraffin ratio. Future work will focus on improving selectivity through oxidation–reduction cycles. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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19 pages, 39581 KiB

Open AccessArticle

Fischer–Tropsch Synthesis: Study of Different Carbon Materials as Cobalt Catalyst Support

by Mingsheng Luo, Shuo Li, Zuoxing Di, He Li, Qinglong Liu, Baozhong Lü, Aimei Wang, Buchang Shi and Iltaf Khan

Reactions 2021, 2(1), 43-61; https://doi.org/10.3390/reactions2010005 - 10 Mar 2021

Cited by 7 | Viewed by 3823

Abstract

In this work, cobalt Fischer–Tropsch synthesis (FTS) catalyst supported on various carbon materials, i.e., carbon nanotube (CNT), activated carbon (AC), graphene oxide (GO), reduced graphene oxide (rGO), and carbon nanofiber (CNF), were prepared via impregnation method. Based on TGA, nitrogen physisorption, XRD, Raman spectroscopy, H₂-TPR, NH₃-TPD, ICP, SEM, and TEM characterization, it is confirmed that Co₃O₄ particles are dispersed uniformly on the supports of carbon nanotube, activated carbon and carbon nanofiber. Furthermore, the FT catalyst performance for as-prepared catalysts was evaluated in a fixed-bed reactor under the condition of H₂:CO = 2:1, 5 SL·h⁻¹·g⁻¹, 2.5 MPa, and 210 °C. Interestingly, the defined three types of carbon materials exhibit superior performance and dispersion compared with graphene oxide and reduced graphene oxide. The thermal stability and pore structure of the five carbon materials vary markedly, and H₂-TPR result shows that the metal–support interaction is in the order of Co/GO > Co/CNT > Co/AC > Co/CNF > Co/rGO. In brief, the carbon nanofiber-supported cobalt catalyst showed the best dispersion, the highest CO conversion, and the lowest gas product but the highest heavy hydrocarbons (C₅₊) selectivity, which can be attributed to the intrinsic property of CNF material that can affect the catalytic performance in a complicated way. This work will open up a new gateway for cobalt support catalysts on various carbon-based materials for Fischer–Tropsch Synthesis. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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19 pages, 2302 KiB

Open AccessArticle

Effect of Changing Amounts of Promoters and Base Fe Metal in a Multicomponent Catalyst Supported on Coal-Based Activated Carbon for Fischer–Tropsch Synthesis

by Soumya J. Gujjar, Avinashkumar V. Karre, Alaa Kababji and Dady B. Dadyburjor

Reactions 2021, 2(1), 11-29; https://doi.org/10.3390/reactions2010003 - 1 Feb 2021

Cited by 6 | Viewed by 2822

Abstract

The effect of varying the amounts of metals Fe, Cu, K, and Mo was studied on a catalyst supported on activated carbon (AC), which is an item of novelty of this paper. The base-case catalyst contains 16% Fe, 0.9% K, 6% Mo, and 0.8% Cu relative to the AC support. For all of the catalysts used, alcohol production is small. The production of hydrocarbons depends upon the amount of Fe and other promoters used. The amount of Fe was increased from 0% to 32% on the catalyst containing base-case amounts of the other materials. While 0% Fe shows no activity towards Fischer–Tropsch synthesis (FTS), 32% Fe shows a marginal increase in FTS activity when compared with 16% Fe. Furthermore, the amount of K was increased from 0% to 1.8%, with the other metals in their base-case amounts. The selectivity of C₁–C₄ decreases with the addition of K, while the selectivity of C₅₊ increases. Analogously, the amount of Mo was increased from 0% to 12%. A small amount of Mo results in an increase in FTS activity but decreases with the addition of more Mo. Cu on the catalyst was increased from 0% to 1.6%, with 0.8% Cu proving optimum for FTS. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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15 pages, 2794 KiB

Open AccessArticle

Hydrocracking of Polyethylene to Jet Fuel Range Hydrocarbons over Bifunctional Catalysts Containing Pt- and Al-Modified MCM-48

by Yanyong Liu

Reactions 2020, 1(2), 195-209; https://doi.org/10.3390/reactions1020014 - 20 Dec 2020

Cited by 12 | Viewed by 3705

Abstract

A low-density polyethylene was hydrocracked to liquid hydrocarbons in autoclave reactors over catalysts containing Pt- and Al-modified MCM-48. Two kinds of Al-modified MCM-48 were synthesized for the reaction: Al-MCM-48 was synthesized using a sol–gel method by mixing Al(iso-OC₃H₇)₃ with Si(OC₂H₅)₄ and surfactant in a basic aqueous solution before hydrothermal synthesis, and Al/MCM-48 was synthesized using a post-modification method by grafting Al³⁺ ions on the surface of calcined Al/MCM-48. X-ray diffraction (XRD) patterns indicated that both Al-MCM-48 and Al/MCM-48 had a cubic mesoporous structure. The Brunauer–Emmett–Teller (BET) surface areas of Al-MCM-48 and Al/MCM-48 were larger than 1000 m²/g. ²⁷Al Magic Angle Spinning-NMR (MAS NMR) indicated that Al³⁺ in Al-MCM-48 was located inside the framework of mesoporous silica, but Al³⁺ in Al/MCM-48 was located outside the framework of mesoporous silica. The results of ammonia temperature-programmed desorption (NH₃-TPD) showed that the acidic strength of various samples was in the order of H-Y > Al/MCM-48 > Al-MCM-48 > MCM-48. After 4 MPa H₂ was charged in the autoclave at room temperature, 1 wt % Pt/Al/MCM-48 catalyst showed a high yield of C₉−C₁₅ jet fuel range hydrocarbons of 85.9% in the hydrocracking of polyethylene at 573 K for 4 h. Compared with the reaction results of Pt/Al/MCM-48, the yield of light hydrocarbons (C₁−C₈) increased over Pt/H-Y, and the yield of heavy hydrocarbons (C₁₆−C₂₁) increased over Pt/Al-MCM-48 in the hydrocracking of polyethylene. The yield of C₉−C₁₅ jet fuel range hydrocarbons over the used catalyst did not decrease compared to the fresh catalyst in the hydrocracking of polyethylene to jet fuel range hydrocarbons over Pt/Al/MCM-48. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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17 pages, 9100 KiB

Open AccessArticle

Production of Fuels and Chemicals from a CO₂/H₂ Mixture

by Yali Yao, Baraka Celestin Sempuga, Xinying Liu and Diane Hildebrandt

Reactions 2020, 1(2), 130-146; https://doi.org/10.3390/reactions1020011 - 19 Nov 2020

Cited by 5 | Viewed by 3810

Abstract

In order to explore co-production alternatives, a once-through process for CO₂ hydrogenation to chemicals and liquid fuels was investigated experimentally. In this approach, two different catalysts were considered; the first was a Cu-based catalyst that hydrogenates CO₂ to methanol and CO and the second a Fisher–Tropsch (FT) Co-based catalyst. The two catalysts were loaded into different reactors and were initially operated separately. The experimental results show that: (1) the Cu catalyst was very active in both the methanol synthesis and reverse-water gas shift (R-WGS) reactions and these two reactions were restricted by thermodynamic equilibrium; this was also supported by an Aspen plus simulation of an (equilibrium) Gibbs reactor. The Aspen simulation results also indicated that the reactor can be operated adiabatically under certain conditions, given that the methanol reaction is exothermic and R-WGS is endothermic. (2) the FT catalyst produced mainly CH₄ and short chain saturated hydrocarbons when the feed was CO₂/H₂. When the two reactors were coupled in series and the presence of CO in the tail gas from the first reactor (loaded with Cu catalyst) significantly improves the FT product selectivity toward higher carbon hydrocarbons in the second reactor compared to the standalone FT reactor with only CO₂/H₂ in the feed. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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Review

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31 pages, 2378 KiB

Open AccessReview

Fischer–Tropsch Synthesis for Light Olefins from Syngas: A Review of Catalyst Development

by Arash Yahyazadeh, Ajay K. Dalai, Wenping Ma and Lifeng Zhang

Reactions 2021, 2(3), 227-257; https://doi.org/10.3390/reactions2030015 - 21 Jul 2021

Cited by 39 | Viewed by 9019

Abstract

Light olefins as one the most important building blocks in chemical industry can be produced via Fischer–Tropsch synthesis (FTS) from syngas. FT synthesis conducted at high temperature would lead to light paraffins, carbon dioxide, methane, and C₅₊ longer chain hydrocarbons. The present work focuses on providing a critical review on the light olefin production using Fischer–Tropsch synthesis. The effects of metals, promoters and supports as the most influential parameters on the catalytic performance of catalysts are discussed meticulously. Fe and Co as the main active metals in FT catalysts are investigated in terms of pore size, crystal size, and crystal phase for obtaining desirable light olefin selectivity. Larger pore size of Fe-based catalysts is suggested to increase olefin selectivity via suppressing 1-olefin readsorption and secondary reactions. Iron carbide as the most probable phase of Fe-based catalysts is proposed for light olefin generation via FTS. Smaller crystal size of Co active metal leads to higher olefin selectivity. Hexagonal close-packed (HCP) structure of Co has higher FTS activity than face-centered cubic (FCC) structure. Transition from Co to Co₃C is mainly proposed for formation of light olefins over Co-based catalysts. Moreover, various catalysts’ deactivation routes are reviewed. Additionally, techno-economic assessment of FTS plants in terms of different costs including capital expenditure and minimum fuel selling price are presented based on the most recent literature. Finally, the potential for global environmental impacts associated with FTS plants including atmospheric and toxicological impacts is considered via lifecycle assessment (LCA). Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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16 pages, 1639 KiB

Open AccessReview

Effects of Structure and Particle Size of Iron, Cobalt and Ruthenium Catalysts on Fischer–Tropsch Synthesis

by Wenping Ma and Ajay K. Dalai

Reactions 2021, 2(1), 62-77; https://doi.org/10.3390/reactions2010006 - 19 Mar 2021

Cited by 12 | Viewed by 3904

Abstract

This review emphasizes the importance of the catalytic conversion techniques in the production of clean liquid and hydrogen fuels (XTF) and chemicals (XTC) from the carbonaceous materials including coal, natural gas, biomass, organic wastes, biogas and CO₂. Dependence of the performance of Fischer–Tropsch Synthesis (FTS), a key reaction of the XTF/XTC process, on catalyst structure (crystal and size) is comparatively examined and reviewed. The contribution illustrates the very complicated crystal structure effect, which indicates that not only the particle type, but also the particle shape, facets and orientation that have been evidenced recently, strongly influence the catalyst performance. In addition, the particle size effects over iron, cobalt and ruthenium catalysts were carefully compared and analyzed. For all Fe, Co and Ru catalysts, the metal turnover frequency (TOF) for CO hydrogenation increased with increasing metal particle size in the small size region i.e., less than the size threshold 7–8 nm, but was found to be independent of particle size for the catalysts with large particle sizes greater than the size threshold. There are some inconsistencies in the small particle size region for Fe and Ru catalysts, i.e., an opposite activity trend and an abnormal peak TOF value were observed on a Fe catalyst and a Ru catalyst (2 nm), respectively. Further study from the literature provides deeper insights into the catalyst behaviors. The intrinsic activity of Fe catalysts (10 nm) at 260–300 °C is estimated in the range of 0.046–0.20 s⁻¹, while that of the Co and Ru catalysts (7–70 nm) at 220 °C are 0.1 s⁻¹ and 0.4 s⁻¹, respectively. Full article

(This article belongs to the Special Issue Catalytic Conversion of Carbonaceous Materials to Fuels and Chemicals)

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