High Gas Hourly Space Velocity Research Articles

Dynamic Reconstruction of Yttrium Oxide-Stabilized Cobalt-Loaded Carbon-Based Catalysts During Thermal Ammonia Decomposition.

Hydrogen production from the decomposition of ammonia is considered an effective approach for addressing challenges associated with hydrogen storage and transportation. However, their relatively high energy consumption and low efficiency hinder practical multi-scenario applications. In this study, Y2O3-stabilized catalysts with Co-loaded onto porous nitrogen-doped carbon (Y2O3-Co/NC) are synthesized by pyrolysis of Y(NO3)3-modified ZIF-67 under an inert atmosphere, followed by annealing in a reducing environment. The introduction of Y2O3 enhanced the recombination and desorption of N atoms and facilitated the gradual dehydrogenation of NHx on the catalyst surface, resulting in improved catalytic activity for the thermal decomposition of ammonia. Benefitting from the electron-donating properties of Y2O3 and N-doped carbon, the optimized catalyst achieved a remarkable NH3 conversion efficiency of 92.3% at a high gas hourly space velocity of 20000 cm3· ·h-1 with an encouraging H2 production rate of 20.6 mmol· ·min-1 at 550°C. Moreover, the synthesized catalyst undergoes a fast-dynamic reconstruction process, resulting in exceptionally stable catalytic activity during the thermal decomposition of ammonia, rendering it a promising candidate for carbon-free energy thermocatalytic conversion technology.

Design of dual-channel Swiss-roll reactor for high-performance hydrogen production from ethanol steam reforming through waste heat valorization

Steam reforming is one of the most economical and efficient methods for hydrogen production. However, one of its glaring issues is the heat supply, which is used to maintain the reactions. Among reactors for hydrogen production, Swiss-roll reactors have exhibited exceptional performance in sustaining the heat required for reactions. Furthermore, heat supply via waste heat recovery has been an attractive industrial prospect for improving the sustainability of hydrogen production. This study proposes a design of a novel Swiss-roll reactor with dual channels to harvest waste heat from the flue gas to sustain the steam reforming reactions. Ethanol is used as a feedstock due to its environmentally benign properties. Numerical simulations are conducted to establish the reactor's catalytic reactions and heat transfer phenomena under the variations of gas hourly space velocity (GHSV), steam-to-ethanol (S/E) ratio, and inlet flue gas temperature. Heat recovery improves at higher GHSVs and lower S/E ratios at the cost of less efficient hydrogen production, while high inlet flue gas temperature improves heat recovery and hydrogen production. The novel reactor design can fulfill complete ethanol conversion maintained by heat recovered from waste flue gas, achieving 86.6 % hydrogen production efficiency and 72.7 % heat recovery under optimal operating conditions.

Study on Novel SCR Catalysts for Denitration of High Concentrated Nitrogen Oxides and Their Reaction Mechanisms

With the rapid development of industrialization, the emission of nitrogen oxides (NOx) has become a global environmental issue. Uranium is the primary fuel used in nuclear power generation. However, the production of uranium, typically based on the uranyl nitrate method, usually generates large amounts of nitrogen oxides, particularly NO2, with concentrations in the exhaust gas exceeding 10,000 ppm. High concentrations of nitrogen dioxide are also produced during silver electrolysis processing and the treatment of waste electrolyte solutions. Traditional V-W/TiO2 NH3-SCR catalysts typically exhibit high catalytic activity at temperatures ranging from 300 to 400 °C, under conditions of low NOx concentrations and high gas hourly space velocity. However, their performance is not satisfying when reducing high concentrations of NO2. This study aims to optimize the traditional V-W/TiO2 catalysts to enhance their catalytic activity under conditions of high NO2 concentrations (10,000 ppm) and a wide temperature range (200–400 °C). On the basis of 3 wt% Mo/TiO2, various loadings of V2O5 were selected, and their catalytic activities were tested. Subsequently, the optimal ratios of active component vanadium and additive molybdenum were explored. Simultaneously, doping with WO3 for modification was selected in the V-Mo/TiO2 catalyst, followed by activity testing under the same conditions. The results show that: the NOx conversion rates of all five catalysts increase with temperature at range of 200–400 °C. Excessive loading of MoO3 decreased the catalytic performance, with 5 wt% being the optimal loading. The addition of WO3 significantly enhanced the low-temperature activity of the catalysts. When the loadings of WO3 and MoO3 were both 3 wt%, the catalyst exhibited the best denitrification performance, achieving a NOx conversion rate of 98.8% at 250 °C. This catalyst demonstrates excellent catalytic activity in reducing very high concentration (10,000 ppm) NO2, at a wider temperature range, expanding the temperature range by 50% compared to conventional SCR catalysts. Characterization techniques including BET, XRD, XPS, H2-TPR, and NH3-TPD were employed to further study the evolution of the catalyst, and the promotional mechanisms are explored. The results revealed that the proportion of chemisorbed oxygen (Oα) increased in the WO3-modified catalyst, exhibiting lower V reduction temperatures, which are favorable for low-temperature denitrification activity. NH3-TPD experiments showed that compared to MoOx species, surface WOx species could provide more acidic sites, resulting in stronger surface acidity of the catalyst.

Resistive Heating Catalytic Micro-Reactor for Process Intensified Fuel Reforming to Hydrogen

Abstract Process intensification of fuel reforming using micro-reactors has become crucial for feed flexibility in H2 production for fuel cells. In the literature on microreactors, energy supply for these endothermic reactions has faced limitations, relying on external heating, or autothermal operation. This paper explores a novel approach using a thin-film catalytic heater to develop micro-reactors. The study focuses on dry methane reforming in a simplified micro-reactor where thermal energy is supplied through electric resistive heating of a thin carbon sheet with a catalyst applied to its surface. The thin catalytic heated layer inside the reactor minimizes energy losses and the reactor footprint. Power input was varied from 90-225 W to understand its impact on the reactor temperature, CH4 conversion, H2 and CO yields. Fast thermal response times were achieved using the carbon paper as thin film for heating. Ni/MgO impregnated onto carbon paper was utilized as the catalytic heating element which resulted in CH4 conversions greater than 60% at temperature above750 K. Influence of operating conditions such as the input molar ratio of CO2/CH4, and gas hourly space velocity (GHSV) were also investigated to understand the scope of the catalyst in this setup. High GHSVs (592,885 and 948,617 mL/(hr.gcatalyst)) were tested to understand the throughput achievable using this setup. This approach demonstrates improved scope and feasibility for further intensification compared to conventionally heated microreactors. The research paves the way for efficient and compact micro-reactors for fuel reforming processes.

Introducing a novel catalyst for efficient conversion of CO2 into syngas through reverse-water-gas-shift (RWGS) reactions based on highly mesoporous structures MCM-41: Influence of the Fe incorporation

The RWGS is the first step in CO2 hydrogenation. This process converts CO2 into valuable compounds, such as methanol, to address the global issue of CO2 emissions. In this research, the performance of a Cu-Fe bimetallic catalyst mounted onto MCM-41 support in RWGS was investigated. Our results demonstrate that MCM-41′s high specific surface area is advantageous for dispersing active metals and preventing their sintering. The Cu-Fe supported on MCM-41 samples are characterized by Scanning Electron Microscopy (SEM), ex situ X-ray Diffraction (XRD), Brunner–Emmet–Teller (BET), and Temperature Programmed Reduction (TPR). In order to investigate the catalytic activity, key variables including a temperature range of 400–600 °C, different H2/CO2 ratios, and various gas hourly space velocities (GHSV) at atmospheric pressure were assessed. In this study, excellent CO2 conversion was attained at a high GHSV (96,000 ml g-1h−1), which is advantageous for the design of smaller reactor volumes. In comparison to industrial Copper-Zinc catalysts and iron-free copper-supported MCM-41 catalysts, which suffer from a high sintering rate at temperatures above 300 °C, adding Iron (Fe) to the copper could increase the catalyst's activity and stability in terms of CO2 conversion and CO selectivity due to the formation of a Cu-Fe alloy. The novelty of this study lies in the assessment of the benefits afforded by bimetallic Cu-Fe catalysts in conjunction with high surface area MCM-41. Also, three different ratios of Cu-Fe (10-1, 7-1, 4-1) were considered for our experiments. The Cu-Fe = 10-1 ratio reached the highest CO2 conversion and CO selectivity value in 600 °C with amounts of 49 % and 99.7 %, respectively.

Constructing Heterointerfaces in Dual-Phase High-Entropy Oxides to Boost O2 Activation and SO2 Resistance for Mercury Removal in Flue Gas.

The low O2 activation ability at low temperatures and SO2 poisoning are challenges for metal oxide catalysts in the application of Hg0 removal in flue gas. A novel high-entropy fluorite oxide (MgAlMnCo)CeO2 (Co-HEO) with the second phase of spinel is synthesized by the microwave hydrothermal method for the first time. A high efficiency of Hg0 removal (close to 100%) is achieved by Co-HEO catalytic oxidation at temperatures as low as 100 °C and in the atmosphere of 145 μg m-3 Hg0 at a high GHSV (gas hourly space velocity) of 95,000 h-1. According to O2-TPD and in situ FT-IR, this extremely superior catalytic oxidation performance at low temperatures originates from the activation ability of Co-HEO to transform O2 into superoxide and peroxide, which is promoted by point defects induced from the spinel/fluorite heterointerfaces. Meanwhile, SO2 resistance of Co-HEO for Hg0 removal is also improved up to 2000 ppm due to the high-entropy-stabilized structure, construction of heterointerfaces, and synergistic effect of the multicomponents for inhibiting the oxidation of SO2 to surface sulfate. The design strategy of the dual-phase high-entropy material launches a new route for metal oxides in the application of catalytic oxidation and SO2 resistance.

New insights into the effect of polyvinyl alcohol on Co3O4 spinel oxide catalyst for N2O decomposition

Polyvinyl alcohol (PVA)-assisted precipitation method offered surface modification Co3O4 spinel oxides which were applied to catalytic N2O decomposition. PVA was added in the preparation process and endowed catalysts with changes in surface metal ions valance state properties, i.e. Co2+ ions which served as active centers. Co3O4 adding PVA (Co3O4-P) showed superior performance for catalytic N2O decomposition with a high gas hourly space velocity of 400,000 h−1. Co2+ ion quantities were positively correlated to catalytic performance which was inseparable from PVA superhydrophobicity and reducibility during the preparation process. Moreover, density functional theory (DFT) calculation revealed N2O preferable adsorption on Co2+ sites whether near oxygen vacancies or not, which indirectly affirmed the reason Co3O4-P with superior catalytic N2O decomposition property. Our research gave more evidence to N2O decomposition active sites from atom-scale for Co3O4 spinel oxides and provided a novel pathway for high-performance catalyst preparation.

Adsorbed oxygen atoms for improving the oxidative dehydrogenation of ethane over B-site-doped layered perovskite La2Ti2O7

In this study, Nd, Ga, and Sm were used to partially replace Ti in layered perovskite La2Ti2O7 (A2B2O7 type) with the aim of developing a highly efficient low-temperature catalyst for the oxidative dehydrogenation of ethane (ODHE). Ethylene was successfully produced by the ODHE over the modified catalysts at temperatures of as low as 600 °C, and the Ga-doped catalyst exhibited the highest ethylene yield of 16.9 % at 625 °C with a high gas hourly space velocity of 35,273 h−1 and short reactant–catalyst contact time of 0.1 s. Thermal activation improved the ethylene yield to 33.6–39.4 % at 650–700 °C with a short contact time (<0.1 s) and productivity of approximately 10 gethylene·gcatalyst−1·h−1, which exceeds reported values. However, the pure catalytic activity could not be depicted at higher temperatures (>700 °C) because the reaction became more complex owing to thermally activated processes such as thermal dehydrogenation, thermal–oxidative dehydrogenation, and reforming reactions. The effects of B-site doping were explored through in situ characterization and density functional theory calculations, and a mechanism for the ODHE was proposed based on the results. Adsorbed oxygen atoms, which form by the dissociation of molecular oxygen at high temperatures, are responsible for the selective dehydrogenation of ethane to ethylene. Overall, the electronic modification of the B-site doped La2Ti2O7 catalysts improved the catalytic activity at 525–575 °C, and the experimental and calculation results confirmed that dissociatively adsorbed oxygen atoms were responsible for the improved ODHE.

Boosting the activity of In-H-SSZ-13 via tuning acid sites for synergistic abatement of NOx and CH4

Selective catalytic reduction of NO by CH4 (CH4-SCR) is a desirable denitration technology for liquefied natural gas (LNG)-powered vehicles and ships, and efficient catalysts have been explored. However, enhancement of the catalytic performance via tuning acid sites of the zeolites is rarely reported. In this work, In-H-SSZ-13 catalysts were prepared via ion exchange method, and the acid sites in the catalysts were adjusted through pre-treatment process of (NH4)2SO4. The activity of the catalyst boosted with improvement of the acid sites in the catalysts, and the activation energy of the reaction decreased from 82.1 to 63.9 kJ/mol over the catalysts. In situ DRIFTS analysis confirmed that more acid sites could facilitate the adsorption and activation of CH4, and R-NCO was a vital intermediate product in the CH4-SCR reaction. The effects of In loading and reaction conditions on the performance of the catalysts were also investigated, and the NO and CH4 conversions reached 75 % and 99 % at 505 °C with a high gas hourly space velocity (GHSV) of 80,000 h−1 over the optimized In-H-SSZ-13 catalyst, respectively.

CO2 hydrogenation over Ru hydrotalcite-derived catalysts

The hydrogenation of CO2 over Ru catalysts is structure sensitive, the selectivity of the process can be driven either to the production of CH4 or CO depending on Ru particles and support features. Herein, Ru-based MgAl-HT (HT=hydrotalcite) derived catalysts with different Ru loadings (0.5, 1.0 and 2.0 wt%) and promoted with La3+ were prepared, characterized, and tested for CO2 methanation at high Gas Hourly Space Velocity values (480 L/gcat h) feeding a CO2/H2/N2 = 1/4/1 v/v mixture. The MgAlOx mixed oxide obtained after calcination at 600 °C and reduction provided weak, medium and mainly strong basic sites, able to activate the CO2 molecule, and hosted very small Ru nanoparticles (1–3 nm). However, the catalysts displayed a low activity in the low temperature range and a poor selectivity to CH4. The addition of La3+, despite contributing to the basicity, did not have any significant effect on performance. In a comparison between Ru- and Ni-HT-derived catalysts, tested under similar reaction conditions, Ni largely overperformed Ru.

The promotion of NH3-SCR performance and its mechanism on Sm modified birnessite

To develop novel NH3-SCR catalysts with low-temperature and high-efficency, a series of birnessite (δ-MnO2) catalysts with different Sm doping by methanol reduction are synthesized. The results showed that the introduction of Sm successfully inhibited the crystallization of MnOX, promoted the specific surface area, the contents of chemisorbed oxygen species and the formation of surface acid sites. It also increased the relative content of (Mn4+ + Mn3+)/Mn, which was beneficial to low-temperature SCR activity. The catalytic performance of xSm/Mn (δ-MnO2 based with xSm doping) catalysts was evaluated by NH3-SCR performances. Among them, 0.05 Sm/Mn showed 100% NOX conversion and high N2 selectivity compared to the other Sm addition catalysts within the operating low-temperature window (25–200 °C), at a high GHSV (gas hourly space velocity) of 60,000 h−1. The modified 0.05 Sm/Mn catalysts followed the L-H and E-R reaction mechanisms and were dominated by L-H, as revealed by in-situ DRIFTs analysis.

Syngas to FCC-like gasoline range hydrocarbons with upgraded light olefin selectivity catalyzed by readily synthesized Fe-MOF

The global trend toward sustainability is due to the growing demand for synthetic chemicals and fuels relying on fossil crude oil with the associated concerns of climate change. The Fischer-Tropsch synthesis (FTS) process is a key sustainable pathway for supplying light olefins, gasoline, and other petrochemicals using green hydrogen and energy. Here we report a simple, green, cost-effective synthesis strategy to prepare an iron-based metal–organic framework (Fe-BTC MOF) at room temperature with a remarkable porous structure analogous to the commercially available Basolite F300. The catalyst shows a 97% syngas conversion to gasoline-range hydrocarbons (C5-C12) at high temperatures, with a selectivity of 48.3%, yield of 28%, low methane selectivity (15.5%) and low C13+ selectivity (1%). In addition, the catalyst is 29% selective to light olefin (C2-C4=), yielding 17%, besides an olefin/paraffin ratio (O/P) of 4.3 with 81% olefin selectivity of the C2-C4 fraction. The resulting gasoline is equivalent to gasoline produced by Fluid Catalytic Cracking (FCC) of crude oil. The highest C5-C12 selectivity reached 63.6%, yielding 12% at 29% CO conversion. The Fe-BTC/C catalyst showed excellent stability for time on stream >100 h and a high gas hourly space velocity (GHSV) value of 20000 mL g-1cat h−1 with an Fe-time yield of 165 µmolCO g-1Fe s−1. The prepared Fe-BTC catalyst, with a 2-fold larger pore volume than the previously prepared Fe-MIL-88B catalyst, has a higher olefin production capability by 2-fold, 7-fold higher O/P for the light fraction and 2.3-fold higher C5+ selectivity. The sustainable synthesis of catalysts with improved porous structure may significantly foster FTS technology for being economically practical to be scaled up and commercialized for national fuel and olefin production projects.

Thiol-grafted MnOx/TiO2 as a dual-site adsorbent for removal of Hg0 from simulated coal-fired flue gas

Emissions of elemental mercury (Hg0) from coal-fired power plant have become a great threaten to the ecosystems. Adsorption is a practical strategy for abating Hg0, but limited Hg0-targeted sites is a stumbling block to developing high-efficiency adsorbents. This work aims to design an efficient adsorbent for Hg0 purification at high gas hourly space velocities (GHSV) is achieved by co-implanting porous TiO2 with inorganic–organic dual functional sites (SH and MnOx). The 2SH-MnOx/TiO2 prepared at SH: MnOx ratios of 2:6 is demonstrated a Hg0 removal efficiency of 90 % at 175 °C under a GHSV of 120,000 h−1. Based on Hg-Temperature Program Desorption (Hg-TPD) analysis, the adsorbed Hg0 converted to HgS and HgO at the SH and MnOx sites of the adsorbents, respectively. The existence of MnOx was revealed to facilitate the generation of HgS. Theoretical calculations suggested that the co-existence of SH and MnOx promotes Hg0 adsorption and boost electrons transfer from Hg0 to adsorbent surface. This study provides a new prospect in developing an advanced alternative adsorbent to increase the efficiency of Hg0 removal from coal-combustion flue gas.

Synergistic Catalysis at the Ni/ZrO2–x Interface toward Low-Temperature CO2 Methanation

The CO2 methanation reaction, which achieves the carbon cycle and gains value-added chemicals, has attracted much attention, but the design and exploitation of highly active catalysts remain a big challenge. Herein, zirconium dioxide-supported Ni catalysts toward low-temperature CO2 methanation are obtained via structural topological transformation of NiZrAl-layered double hydroxide (LDH) precursors, which have the feature of an interfacial structure (Ni-O-Zr3+-Vö) between Ni nanoparticles and ZrO2-x support (0 < x < 1). The optimized catalyst (Ni/ZrO2-x-S2) exhibits exceptional CO2 conversion (∼72%) at a temperature as low as 230 °C with a ∼100% selectivity to CH4, without obvious catalyst deactivation within a 110 h reaction at a high gas hourly space velocity of 30,000 mL·g-1·h-1. Markedly, the space-time yield of CH4 reaches up to ∼0.17 ·gcat-1·h-1, which is superior to previously reported Ni catalysts evaluated under similar reaction conditions. Both in situ/operando investigations (diffuse reflectance infrared Fourier transform spectroscopy and X-ray absorption fine structure) and catalytic evaluations substantiate the interfacial synergistic catalysis at the Ni/ZrO2-x interface: the Zr3+-Vö facilitates the activation adsorption of CO2, while the H2 molecule experiences dissociation at the metallic Ni sites. This work demonstrates that the metal-support interface effect plays a key role in improving the catalytic behavior toward CO2 methanation, which can be extended to other high-performance heterogeneous catalysts toward structure-sensitive systems.

Hydrogen production from waste-derived synthesis gas over Ni(x)Fe(3-x)-CeO2 catalyst: optimization of Ni/Fe ratio

In this study, the effect of the Ni/Fe molar ratio on the Ni(x)Fe(3-x)-CeO2 catalyst was investigated for the high-temperature water-gas shift reaction, which produces hydrogen from waste-derived synthesis gas. The catalysts were synthesized via a co-precipitation method, using different Ni/Fe molar ratios (0.5:2.5, 1.0:2.0, 1.5:1.5, 2.0:1.0, and 2.5:0.5). The physicochemical properties of these catalysts were analyzed by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), temperature-programmed reduction using hydrogen (H2-TPR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and H2-O2 pulse analyses to determine their reaction performance. The Ni1.0Fe2.0-CeO2 catalyst exhibited the highest activity (Xco = 88%, T = 500 °C) without any side reactions at a high gas hourly space velocity of 41,823 mL·g−1 h−1, compared to the other catalysts tested, owing to its high oxygen vacancies and oxygen storage capacity (OSC). In addition, when the Ni/Fe molar ratio was higher than 1, a side reaction (methanation) occurred. Therefore, it was concluded that the Ni1.0Fe2.0-CeO2 catalyst is optimal for hydrogen production via the high-temperature water-gas shift reaction from waste-derived synthesis gas.

Dual confinement of LaCoOx modified Co nanoparticles for superior and stable ammonia decomposition

In this work, we report the rational design of amorphous LaCoOx modified Co nanoparticles confined in both nitrogen-doped carbon (NC) matrix and two-dimensional (2D) mesoporous silica (LaCoOx/Co@NC/SBA-15(2D)) via in situ confined pyrolysis of nano-sized La doped ZIF-67 in the mesopores of SBA-15(2D) as a novel dual-spatially-confined composite catalyst with superior activity and stability toward ammonia decomposition to produce hydrogen. It achieves a NH3 conversion efficiency close to 100 % at a high gas hourly space velocity (GHSV) of 60,000 gcat-1 h-1 with an encouraging H2 production rate of 446 mmol gCo-1 min-1 at 600 ℃ and can maintain stable catalytic activity for 200 h, almost outperforming all Co-based catalysts reported so far. Various characterizations and theoretical calculation results reveal that the outstanding ammonia decomposition performance mainly origins from the dual-spatially-confined configuration, fully exposed active sites and high mass transfer efficiency, and the synergy of amorphous LaCoOx, Co nanoparticles and NC matrix.

Crystal facets engineering of γ-MnO2 catalysts for remarkable enhancement of formaldehyde removal efficiency

Formaldehyde (HCHO) is a hazardous gas in indoor spaces because it is carcinogenic to human body. The removal of HCHO is of great significance for breathing safety. Facets engineering is a novel strategy to synthesize efficient catalysts, for which the selective exposed active facets on the catalysts can considerably improve catalytic performance. In this work, we synthesized three γ-MnO2 catalysts with selective exposures of (300), (160) and (131) crystal facets, the γ-MnO2-300 exposing (300) crystal facet had the best HCHO oxidation activity than the γ-MnO2-160 and γ-MnO2-131 exposing (160) and (131) crystal facets, respectively. 100 ppm HCHO was completely eliminated under high gas hourly space velocity at 40–45 °C catalyzed by the γ-MnO2-300, which was superior to other MnO2 reported in literatures. Through characterizations of BET, XPS, H2-TPR and O2-TPD etc., the highest surface area, the most active surface lattice oxygen and the most oxygen vacancy on the γ-MnO2-300 surface are assigned to its highest oxidation activity. The work provides a facet engineering method for γ-MnO2 catalyst to full eliminate HCHO at room temperature, which is applicable to facet-oriented catalysts development for other reactions.

Bimetallic cobalt catalysts promoted by La2O3 for the production of high-calorie synthetic gas

A new catalytic route for the production of a high-calorie synthetic gas (40–60 MJ/Nm3), composed by C1-C4 hydrocarbons, has industrial interest for gas applications and locations with high heating requirements. In this work, a series of bimetallic Co-X (X = Ni, Pt and Fe) catalysts supported on La2O3 promoted Al2O3 micro-spheres were evaluated using both CO2 and CO carbon sources under mild temperature (T = 200–300 °C), moderate pressure (P = 10 bar·g) and relatively high gas hourly space velocity (40,000 N mL/gcat·h). Experimental results proved that the incorporation of nickel as a second metal is beneficial for high-calorie gas application. Besides, catalytic results showed that the utilization of CO as carbon source is beneficial in both conversion and C1-C4 hydrocarbon selectivities. Co-Ni presented the most interesting results, leading to a heating value of 57.9 MJ/Nm3 (40.01 % CH4 and 50.04 % C2-C4 hydrocarbon) at 250 °C through CO hydrogenation. The enhanced catalytic performance achieved over bimetallic Co-Ni was attributed to CoNi alloy catalytic activity, high reducibility (73.82 %), active metal content (9.65x10-4 mmol/g) and appropriate acid-basic sites for COx activation. In contrast, the conversion of CO2 to high-calorie gas was found to be more challenging and lower gas heating values were achieved (39.73 MJ/Nm3). In this case, an adapted reactor concept using a dual bimetallic catalyst and different reaction conditions is hereby proposed to shift selectivity towards the targeted products. This findings represent a step forwards in catalytic engineering for the development of high-calorie synthetic gas reactors.

Reactive Separations of CO/CO2 mixtures over Ru–Co Single Atom Alloys

Reactive separations of CO/CO2 mixtures are a promising pathway to lower the energy requirement of CO2 hydrogenation to chemicals and fuels, with applications in the U.S. Navy’s seawater-to-fuel process. With the CO/CO2 feedstock, a challenge is activating CO to produce heavier hydrocarbons while preventing CO2 methanation, requiring low-temperature Fischer-Tropsch synthesis (FTS) catalysts. In this work, we demonstrate that a Ru–Co single atom alloy (SAA) catalyst produces C5+ hydrocarbons at a rate of 11.7 μmol/s/g-cobalt (hexane basis) in a 50/50 CO/CO2 stream with ≤1% CO2 conversion. The reaction operates at a relatively low temperature (200 °C) and high gas hourly space velocity (GHSV: 84,000 mL/g/h) that is compatible with the upstream reverse water-gas shift reaction. Detailed experiments, catalyst characterizations, and density functional theory (DFT) calculations have been conducted to understand the active phase, the role of the Ru dopant, and catalyst restructuring that occurs at elevated temperatures (>200 °C). Ru dopants are found to promote the reduction of Co species, enabling catalytic activity for CO hydrogenation without pre-reduction, but may not enhance the FTS activity or desired C5+ hydrocarbon selectivity.

Construction of Highly Dispersed Cu–P/Cl Active Sites Using Methyldiphenyloxophosphine for Efficient Acetylene Hydrochlorination

To overcome the disadvantages of Cu-based catalysts, such as the low dispersion of active components and insufficient active species, several 15% Cu-Lx/AC catalysts for acetylene hydrochlorination were synthesized based on strong interactions between a ligand and CuCl2 precursors. The introduction of the methyldiphenyloxophosphine (MDPO) ligand effectively modulated the electronic properties of the metal centers, which contributed to the construction of a highly dispersed Cu–P/Cl local structure with Cu1+/Cu2+ as a plausible active center. The sintering of active components in the catalyst may be one of the main reasons for the decrease in catalytic performance. Meanwhile, the enhanced adsorption and activation of the catalyst for C2H2 and HCl molecules resulted in improved coking resistance. The most active catalyst (15% Cu8MDPO1/AC) could achieve a stable acetylene conversion of 97% at 180 °C, a gas hourly space velocity (GHSV) (C2H2) of 180 h–1, and a feed volume ratio (VHCl/VC2H2) of 1.15, outperforming the benchmark catalyst. The excellent activity and stability in a 300 h laboratory test at a high GHSV and a 3414 h industrial sideline test at an industrial GHSV render the 15% Cu8MDPO1/AC catalyst as a reference for the construction of other catalysts from an environmental, economic, and application prospect perspective.