Thermocatalytic Reaction Research Articles

Tandem Thermocatalytic Reaction for CO2 Fixation into Single-Walled Carbon Nanotubes

Tandem Thermocatalytic Reaction for CO₂ Fixation into Single-Walled Carbon Nanotubes

Effective synergistic interaction between InZnZrOx ternary metal oxides and SAPO-34 molecular sieve catalysts for CO2 hydrogenation to light olefins

The synergistic interaction of metal oxides with molecular sieves is essential for the catalytic hydrogenation of carbon dioxide (CO2) into light olefins (C2=–C4=) over bifunctional tandem catalysts. Herein, a series of In2O3-doped InZnZrOx (IZZ) ternary metal oxides was prepared and physically mixed with SAPO-34. The bifunctional catalyst was used in the direct conversion of CO2 to light olefins. The relationship between IZZ oxide structures prepared using different methods and the catalytic performance of bifunctional catalysts was investigated. Moreover, the migration of InOx in ternary metal oxides was revealed. Results revealed that for IZZ oxides prepared via precipitation coating and impregnation, InOx species migrated to the SAPO-34 surface during thermocatalytic reaction due to the dispersion of In2O3 on the ZnZrOx surface and its weak interaction with ZnZrOx. This led to the neutralization of acid centers on SAPO-34 by InOx, thereby destroying the synergistic interaction between the oxides and SAPO-34, resulting in a large amount of unneeded methane and poor light olefin selectivity. However, the co-precipitated IZZ-CP oxides exhibited a ternary solid solution structure and inhibited the migration of InOx. This enhanced CO2 and H2 activation, affording more formate (HCOO*) and methoxide (CH3O*) intermediates that strengthened the synergistic interaction between the oxides and molecular sieves. After optimizing the In2O3 doping amount in IZZ-CP oxide and the reaction conditions, the IZZ-CP/SAPO-34 bifunctional catalyst achieved 17.9 % CO2 conversion, 80.1 % C2=–C4= selectivity, only 7.6 % methane and 44.6 % CO selectivity. It also maintained excellent catalytic stability without significant deactivation after continuous reaction for 80 h.

Hydrothermal Catalytic Transformations of Polymeric Wastes over Zeolite Catalysts Modified with Molybdenum and Tungsten

The article is devoted to the study of the adsorption properties and morphology of new composite catalysts based on acid-activated zeolite heulandite-clinoptilolite of the Kazakhstan Taizhuzgen deposit modified with molybdenum salts (NH4)MoO·4H2O and tungsten (NH4)5H5[H2(WO4)6]·H2O, for the process of thermocatalytic hydrogenation of plastic waste. The study of the developed catalyst by the method of adsorption nitrogen porometry demonstrated the presence of typical type IV isotherms, which indicated the formation of a porous adsorbent by multilayer nitrogen adsorption in the mesopores of the catalyst. The adsorption capacity of the structure formed by the catalyst based on zeolite modified with molybdenum and tungsten, due to the presence of predominantly mesoporous cavities, is able to selectively influence the process of hydrothermocatalytic processing of waste polymers based on polyethylene and polypropylene. The pore size distribution indicates the presence of mesopores and an insignificant number of micropores at low pressure. The catalyst samples were tested in the thermocatalytic hydrogenation reaction of polymer waste. Significant gas formation and predominant content of alkanes, isoalkanes, alkenes and aromatic hydrocarbons in liquid products are shown. It is obviously that the main contribution to the transformations made by mesoporous inclusions in the cavities of the zeolite under study formed during their treatment with molybdenum and tungsten salts.

Cu MOF-biocarbon functional catalysts as adsorbent for oxygen-linked carbon capture via thermo-catalytic pyrolysis: A low-carbon fuel synthesis strategy

Low-carbon fuel synthesis is encouraged as it is environmentally benign and aims to lessen the impact of global warming. This experimental investigation examines the synthesized Bombax ceiba oil (Bio-oil) based pyrolyzed oil utilizing Cu MOF-biocarbon catalysts (0.15 wt.%) via thermo-catalytic cracking and adsorption. The structural and thermal characteristics of the developed Cu MOF - biocarbon catalysts are investigated using Field Emission – Scanning Electron Microscopy/Energy Dispersive Spectroscopy (FE-SEM/EDAX), Attenuated Total Reflectance-Infrared Spectroscopy (ATR-IR), X-Ray Diffraction (XRD), Thermogravimetry-Differential Thermal Analysis (TG-DTA) and Brunauer-Emmett-Teller (BET). Following a thermo-catalytic reaction with a hot plate magnetic stirrer (600 rpm, 100 °C, and 1 h), the oily Cu MOF-biocarbon catalysts are separated from the pyrolyzed green fuel using high-speed centrifugation. The cracking and adsorption of the pyrolyzed green oil compounds are studied using 1H NMR, GC–MS, and thermal conductivity. The results indicate that alkane compounds increase from 3.25 to 6.70 % whereas oxygen incorporated compounds decrease from 96.75 to 93.30 % in the pyrolyzed oil. Furthermore, the GC–MS study shows that the separated oily catalysts adsorb 44.52 % of hydrocarbon (CH) and oxygen-linked (CHO) hydro-carbon compounds. Overall, the newly synthesized Cu MOF-biocarbon is considered as a potential functional catalyst for cracking and adsorption of alkane/oxygen bonded compounds (e.g., CH, CO etc.,), promoting the pyrolyzed oil as low-carbon fuel for better sustainable environment.

Constructing Efficient CuAg Nanoalloys on Ce0.90In0.10Oδ for Methanol Deep Oxidation Catalysis at Low Temperature.

So far, it is still extremely challenging to develop an efficient catalyst for deep oxidation of methanol at low temperature. Herein, we report the construction of the highly dispersed CuAg alloy on the surface of Ce0.90In0.10Oδ nanorods support for catalyzing methanol deep oxidation. The composition, structure and properties of catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results show that the CuxAg100-x/Ce0.90In0.10Oδ alloy catalysts exhibit superior catalytic activity and stability compared to pure Ag/Ce0.90In0.10Oδ, with the highest activity observed for Cu40Ag60/Ce0.90In0.10Oδ, accompanied by the light-off temperature (T50) and full conversion temperature (T90) of 115 and 145 °C, respectively. This is attributed to the synergistic effect of CuAg alloy, which results in electron transfer, generating more Ag0, and enhanced interaction between CuAg alloy and the support, leading to increased Ce3+ content and higher oxygen vacancy concentration. This work successfully applies CuAg alloy catalysts in thermo-catalytic reaction, offering promising prospects for CuAg alloy catalysts in the methanol deep oxidation.

ZSM‐5‐Promoted Co‐Based Light‐Assisted Thermocatalytic Fischer–Tropsch Synthesis Catalyst for Production of Liquid Fuel

Light‐assisted thermocatalytic Fischer–Tropsch synthesis (FTS) provides a more efficient and sustainable approach to synthesizing high‐value chemicals compared to the thermal‐driven FTS. However, producing liquid fuel via cobalt‐based light‐assisted thermocatalytic FTS catalyst poses a challenge since photogenerated electrons increase CO conversion simultaneously with a significant reduction in the selectivity of C5+ product. Herein, a cobalt‐based light‐assisted thermocatalytic FTS catalyst containing ZSM‐5 molecular sieve promoter is prepared by a unique wet chemical reduction method, and the constructed 15%Co/Ta3N5‐ZSM‐5 catalyst exhibits nearly 90% C5+ product selectivity and 63% CO conversion under photothermal condition. Further characterization indicates that the simultaneous increase in the number of active sites and the density of acidic sites in the catalyst is crucial to achieve a simultaneous increase in CO conversion and C5+ product selectivity, which enables the catalyst to produce liquid fuel via light‐assisted thermocatalytic FTS reaction. This work provides an approach to introduce solar energy into the process of liquid fuel production, which can improve the sustainability of the liquid fuel production process.

Plasma‐catalytic synthesis of acrylonitrile from methane and nitrogen

AbstractIn this work, we demonstrate plasma‐catalytic synthesis of hydrogen and acrylonitrile (AN) from CH4 and N2. The process involves two steps: (1) plasma synthesis of C2H2 and HCN in a nominally 1:1 stoichiometric ratio with high yield up to 90% and (2) downstream thermocatalytic reaction of these intermediates to make AN. The effect of process parameters on product distributions and specific energy requirements are reported. If the catalytic conversion of C2H2 and HCN in the downstream thermocatalytic step to AN were perfect, which will require further improvements in the thermocatalytic reactor, then at the maximum output of our 1 kW radiofrequency 13.56 MHz transformer, a specific energy requirement of 73 kWh kgAN−1 was determined. The expectation is that scaling up the process to higher throughputs would result in decreases in specific energy requirement into the predicted economically viable range less than 10 kWh kgAN−1.

Hydrogen's organic genesis

Natural hydrogen exploration has been restricted in scope due to the predominance in thinking that various rock interactions with water in cratonic settings offer the best natural hydrogen sources. The limited exploration findings in these areas in conjunction with advances in the understanding of hydrogen generation via anthropogenic methods suggest that other source alternatives such as organic hydrogen generation need to be revisited. The ideas on the maturation of organic matter may need to be reassessed with respect to hydrogen. It is suggested that an overlapping thermo-catalytic set of processes occurs to produce hydrocarbons and hydrogen. Initially clay reacts with kerogen producing hydrocarbons, hydrogen and amorphous carbon, the alteration of clays releasing hydronium. During the late catagenic phase thermo-catalysis of hydrocarbons by amorphous carbon create shorter chained hydrocarbons and hydrogen whilst amorphous carbon degrades to carbon black. During expulsion of hydrocarbons and hydrogen the permeability of the source rock becomes more heterogeneous, isolating some reactants creating pyrobitumens and other carbonaceous materials. At higher temperatures during metagenesis isolated pyrobitumens and other carbonaceous materials in shales are turned to graphite releasing gaseous hydrocarbons and eventually diatomic hydrogen in a second phase by thermo-catalytic reaction with carbon black. This matches the temperatures and results at which laboratory experiments and petrochemical processes used to generate hydrogen are observed. The current conclusion of the hydrocarbon generation story at the methane preservation limit should be recognized as the start of hydrogen generation and graphitization as the end of the process. Instead of basin exploration focused solely on hydrocarbons and stopping due to concerns of over maturity of source and reservoir, exploration may continue deeper in search of organic hydrogen. This should be noted as a primary hydrogen generation mechanism globally and provide a suitable model to aid hydrogen exploration and lead the energy transition into a hydrogen economy.

Ultra-flexible Al2O3 fibers: A novel catalyst support material for sustainable catalysis

Flexible aluminum oxide (Al2O3) fibers were prepared by the blow spinning method and their potential as a high-temperature catalyst support was investigated. The synthesized Al2O3 fibers exhibited remarkable flexibility in both mechanical compression and recovery tests, which remained intact in a wide temperature range from −196 °C to 1200 °C. Moreover, their low thermal conductivity of 0.030 W K−1∙m−1, demonstrated an outstanding thermal insulation. Subsequently, nickel nanoparticles were uniformly distributed on the surface of the Al2O3 fibers as a self-supporting catalyst using a conventional impregnation method. The resulting self-supporting Ni/Al2O3 catalyst demonstrated remarkable thermo-catalytic performance and re-activation capability at high temperatures for thermocatalytic reaction of dry reforming of methane (DRM). Our findings highlight the potential of pure Al2O3 flexible fibers as a versatile material for various industrial applications, including high-temperature catalysis.

Contrasting Capability of Single Atom Palladium for Thermocatalytic versus Electrocatalytic Nitrate Reduction Reaction.

The occurrence of high concentrations of nitrate in various water resources is a significant environmental and human health threat, demanding effective removal technologies. Single atom alloys (SAAs) have emerged as a promising bimetallic material architecture in various thermocatalytic and electrocatalytic schemes including nitrate reduction reaction (NRR). This study suggests that there exists a stark contrast between thermocatalytic (T-NRR) and electrocatalytic (E-NRR) pathways that resulted in dramatic differences in SAA performances. Among Pd/Cu nanoalloys with varying Pd-Cu ratios from 1:100 to 100:1, Pd/Cu(1:100) SAA exhibited the greatest activity (TOFPd = 2 min-1) and highest N2 selectivity (94%) for E-NRR, while the same SAA performed poorly for T-NRR as compared to other nanoalloy counterparts. DFT calculations demonstrate that the improved performance and N2 selectivity of Pd/Cu(1:100) in E-NRR compared to T-NRR originate from the higher stability of NO3* in electrocatalysis and a lower N2 formation barrier than NH due to localized pH effects and the ability to extract protons from water. This study establishes the performance and mechanistic differences of SAA and nanoalloys for T-NRR versus E-NRR.

Photo‐Driven Hydrogen Production from Methanol and Water using Plasmonic Cu Nanoparticles Derived from Layered Double Hydroxides

AbstractMethanol steam reforming (MSR) is viewed as an important technology in the growth of a future hydrogen economy, with methanol serving as an easily transportable and storable liquid hydrogen carrier. However, the thermocatalytic MSR reaction is energy intensive as it requires high temperatures. Herein, a novel L‐Cu catalyst is successfully fabricated for photo‐driven MSR through reduction of CuAl layered double hydroxide (CuAl‐LDH) nanosheets. L‐Cu offers outstanding activity for the photothermal conversion of methanol and water to hydrogen (160.5 µmol gcat−1 s−1) under ultraviolet‐visible irradiation, with this rate being much higher than that achieved for L‐Cu at the same temperature in the dark. Characterization studies using X‐ray diffraction, X‐ray photoelectron spectroscopy, X‐ray absorption spectroscopy, and high‐resolution transmission electron microscopy determine that L‐Cu catalyst comprise Cu nanoparticles on an amorphous alumina support. Computational calculations reveale that Cu localized surface plasmon resonance effects promote the activation of H2O, thereby underpinning the remarkable hydrogen production rates achieved during photo‐driven MSR. This study introduces a novel photothermal strategy for hydrogen generation from methanol, demonstrating the enormous potential of photothermal catalysis in the chemical and energy sectors.

Kinetic and mechanistic investigations of the oxidation of organics by near-infrared light driven thermocatalytic activation of peroxydisulfate with Fe3O4

The utilization of renewable solar energy through near-infrared (NIR)-driven photothermal catalysts offers a potential novel strategy for environmental remediation. In this work, we reported an initial demonstration of the peroxydisulfate (PDS) activation in oxidative degradation of organics (represented by bisphenol A (BPA)) via a unique NIR light-to-heat conversion effect using cost-effective and biocompatible nanoparticles (NPs). The systematical investigation of the photothermal experiments found that Fe3O4 magnetic NPs exhibit great photothermal conversion efficiency (65.4%) and have the capability to quickly elevate the system temperature to 61°C. The increased reaction temperature leads to the homolytic fission of the OO bond for producing sulfate radical (SO4−) and the derivative hydroxyl radical (OH), as confirmed by the radical quenching and electron paramagnetic resonances (EPR) tests, and in turn accelerates the thermocatalytic degradation reaction of BPA. The BPA degradation reaction rate of the NIR/Fe3O4/PDS system is about 25.8 times and 9.4 times of that in the NIR/PDS and Fe3O4/PDS systems, respectively. Both photothermal heating and surface valence states conversion of Fe2+/Fe3+ on Fe3O4 under dark conditions make a contribution to the observed oxidation reactions. Moreover, this NIR light-to-heat activation system exhibits efficient photocatalytic degradation of BPA molecules in deep water by virtue of the deep penetration capability of NIR light in water, highlighting NIR-driven photothermal catalysts hold the excellent potential to be applied in practical water restoration through PDS activation.

Enhanced Multi-Carbon Selectivity Via Tandem CO2 Electroreduction

Electrifying chemical production is a potential approach to decarbonizing the chemical industry. Currently, 21% of the global greenhouse gas emissions come from the industry sector, while chemical manufacturing accounts for the largest share of industrial carbon emissions1. The electrochemical processes, when powered by renewable electricity, have lower carbon footprints than conventional thermochemical routes. The rapid development of renewable energy provides opportunities for electrifying chemical production and decarbonizing the chemical industry. Among these, electrochemical CO2 reduction reaction (CO2RR) attracted much attention as a potential pathway for carbon utilization and sustainable chemical production. In this presentation, I would like to present a tandem CO2 electroreduction scheme for multicarbon production. A molecular tuning strategy is applied to tune the intermediate binding energy and thus enhance the CO selectivity in the first step2. Then CO2 and CO electroreduction to C2+ products in alkaline conditions are compared, with particular emphasis on carbonate formation and carbon efficiency (i.e., the amount of carbon ended in the desired products divided by the total amount of CO2 consumed)3. The conclusion is that CORR shows specific advantages over CO2RR in the aspects of C2+ selectivity, stability, carbon efficiency, and single-pass conversion. Then oxide-derived Cu plates are chosen for the second step in tandem reduction, which shows a C2+ Faradaic efficiency of 83% at -0.59 V vs RHE. Lastly, we further extend our tandem system to electrocatalytic–thermocatalytic reaction for CO2 conversion to C3 oxygenate4. A 25 cm2 membrane electrode assembly device is coupled with a thermochemical hydroformylation reactor to produce 1-propanol and propanal. A total C3 oxygenate selectivity of ~18% is achieved in the tandem reaction.

Identifying Photocatalytic Active Sites of C2H6 C-H Bond Activation on TiO2 via Combining First-Principles Ground-State and Excited-State Electronic Structure Calculations.

The activation of C-H bonds at low temperatures has attracted widespread interest in heterogeneous catalysis, which involves complex thermocatalytic and photocatalytic reaction processes. Herein, we systematically investigate the photothermal catalytic process of C-H bond activation in C2H6 dehydrogenation on rutile TiO2(110). We demonstrate that the photochemical activity of the C2H6 molecule adsorbed on TiO2(110) is site-sensitive and that C2H6 is more easily adsorbed at the Ti5c site with a lower dehydrogenation energy barrier. The first C-H bond activation of the C2H6 adsorbed at the Ti5c site tends to occur in the ground state, whereas Obr-adsorbed C2H6 is more photoactive during the initial adsorption. During the dehydrogenation of C2H6, the photogenerated electrons are always located at the Ti4+ sites of the TiO2 substrate while the photogenerated holes can be captured by C2H6 to activate the C-H bond.

Enhanced dissociation activation of CO2 on the Bi/Cu(1 1 1) interface by the synergistic effect

Thermocatalytic CO2 reduction reaction (CO2RR) is one of the promising strategies to mitigate CO2 emissions. Meanwhile, understanding the reduction mechanism of CO2 on the catalyst surface is imperative for advancing catalyst design and the eventual industrialization under mild conditions. In this work, the catalytic role of bismuth/copper interface towards CO2RR is elaborately investigated via a combination of near ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS), ambient-pressure scanning tunneling microscopy (NAP-STM) and density function theory (DFT). It is demonstrated that the initial deposition of Bi on Cu results in the formation of Bi-Cu heterogenous structure, while the interface is buried at the thick coverage. Upon CO2 exposure, Bi is oxidized at interface due to the activation of CO2 on Cu sites and subsequent migration of oxygen to Bi, while Cu+ is induced afterwards in annealing acting as the further dissociation site. Compared with the pure Cu(111), the fraction of oxidation including both lattice and defective oxygen is significantly higher on the Bi/Cu interface, indicating the synergistic effect of Bi-Cu interface in the activation of CO2. Thus, our work clearly reveals the dissociation site evolution of the Bi-Cu bimetallic heterostructure and might promote the design of Cu-based catalysts for advancing thermocatalytic CO2RR.

Efficient electrocatalytic acetylene semihydrogenation by electron\u2013rich metal sites in N\u2013heterocyclic carbene metal complexes

Electrocatalytic acetylene semihydrogenation is a promising alternative to thermocatalytic acetylene hydrogenation due to its environmental benignity and economic efficiency, but its performance is far below that of the thermocatalytic reaction because of strong competition from side reactions, including hydrogen evolution, overhydrogenation and carbon–carbon coupling reactions. We develop N–heterocyclic carbene–metal complexes, with electron–rich metal centers owing to the strongly σ–donating N–heterocyclic carbene ligands, as electrocatalysts for selective acetylene semihydrogenation. Experimental and theoretical investigations reveal that the copper sites in N–heterocyclic carbene–copper facilitate the absorption of electrophilic acetylene and the desorption of nucleophilic ethylene, ultimately suppressing the side reactions during electrocatalytic acetylene semihydrogenation, and exhibit superior semihydrogenation performance, with faradaic efficiencies of ≥98 % under pure acetylene flow. Even in a crude ethylene feed containing 1 % acetylene (1 × 104 ppm), N–heterocyclic carbene–copper affords a specific selectivity of >99 % during a 100–h stability test, continuous ethylene production with only ~30 ppm acetylene, a large space velocity of up to 9.6 × 105 mL·gcat−1·h−1, and a turnover frequency of 2.1 × 10−2 s−1, dramatically outperforming currently reported thermocatalysts.

Band-Gap Engineering: A New Tool for Tailoring the Activity of Semiconducting Oxide Catalysts for CO Oxidation.

Cation or anion vacancies in semiconducting oxides usually benefit activity for CO oxidation. To study the nature of vacancy engineering for a thermocatalytic reaction, we adopted lattice doping of cations with varied valence states to construct anion and cation vacancies in n-type and p-type semiconducting CeO2 and NiO, respectively. Doping cations can effectively regulate the number of the vacancies, thus tailoring the activity for CO oxidation. The strong correlation of activation energy and specific activity with a catalyst band gap verified that the nature of vacancy engineering for activity of CeO2 and NiO for CO oxidation can be attributed to tailoring of the band gap. The larger the vacancy amount, the smaller the band gap, and the lower the activation energy, thus giving a higher specific activity. Band-gap engineering, widely used for photocatalytic processes, can be a new tool for tailoring the activity of semiconducting oxide catalysts for thermocatalytic reactions.

Kinetic modeling and reaction pathways for thermo-catalytic conversion of carbon dioxide and methane to hydrogen-rich syngas over alpha-alumina supported cobalt catalyst

This study investigates the kinetic modeling and reaction pathway for the thermo-catalytic conversion of methane (CH4) and Carbon dioxide (CO2) over alpha-alumina supported cobalt catalyst. Rate data was obtained from the thermo-catalytic reaction at a temperature range of 923–1023 K and varying CH4 and CO2 partial pressure (5–50 kPa). The rate data was significantly influenced by the changes in the reaction temperature as well as the CH4 and CO2 partial pressure. To estimate the kinetic parameters, the rate data were fitted with five Langmuir-Hinshelwood kinetic models. The discrimination of the kinetic models using different parameters revealed that the Langmuir-Hinshelwood kinetic model with the assumption of CH4 being associatively adsorbed on a single and CO2 being dissociative adsorbed with bimolecular surface reaction best described the rate data. The analysis of the kinetic model using a non-linear regression solver results in activation energies of 15.88 kJ/mol, 36.78 kJ/mol, 65.51 kJ/mol, and 41.08 kJ/mol for CH4 consumption, CO2 consumption, H2 production, and CO production, respectively. The thermo-catalytic reaction was influenced by carbon as indicated by the rate of carbon deposition which was mainly caused by methane cracking. The reaction pathway for the thermo-catalytic conversion of the CH4 and CO2 over the alpha-alumina supported cobalt catalyst can best be described as by CH4 associative adsorption on the alpha-alumina supported cobalt catalyst single site and CO2 dissociative adsorption with bimolecular surface reaction.

Thermo‐catalytic conversion of greenhouse gases (CO 2 and CH 4 ) to CO‐rich hydrogen by CeO 2 modified calcium iron oxide supported nickel catalyst

In this study, the thermo-catalytic conversion of two principal greenhouse gases (methane and carbon dioxide) to carbon monoxide (CO)-rich hydrogen (H2) is investigated over cerium oxide (CeO2) promoted calcium ferrite supported nickel (Ni/CaFe2O4) catalyst. The CeO2 promoted Ni/CaFe2O4 catalyst was prepared using wet-impregnation technique. To ascertain the physicochemical properties, the as-prepared catalyst was characterized using various instrument techniques. The characterization of the catalysts reveals that CeO2-Ni/CaFe2O4 possesses suitable physicochemical properties for the conversion of methane (CH4) and carbon dioxide (CO2) to CO-rich H2. The thermo-catalytic reaction revealed that the CeO2 promoted Ni/CaFe2O4 catalyst displayed a higher CH4 and CO2 conversions of 90.04% and 91.2%, respectively, at a temperature of 1073 K compared to the unpromoted catalyst. The highest H2 and CO yields of 78% and 76%, respectively, were obtained over the CeO2-Ni/CaFe2O4 at 1073 K and CH4/CO2 ratio of 1. The CeO2 promoted Ni/CaFe2O4 catalyst remained stable throughout the 30 hours time on stream (TOS) while that of the unpromoted Ni/CaFe2O4 catalyst sharply decreased after 22 hours TOS. The characterization of the used catalysts confirms the evidence of carbon depositions on the unpromoted Ni/CaFe2O4 which is solely responsible for its deactivation. Whereas, there was a slightly gasifiable carbon deposited on the CeO2 promoted Ni/CaFe2O4 catalyst which could be ascribed to the interaction effect of the CeO2 promoter on the Ni/CaFe2O4 catalyst.

An Anionic Nanotubular Metal-Organic Framework for High-Capacity Dye Adsorption and Dye Degradation in Darkness.

A metal-organic framework (MOF), named SCNU-Z2, based on a new heterotopic tripodal nitrogen-containing ligand, has been constructed. Due to the replacement of one imidazole group in the reported ligand with one tetrazole group, the charge of the framework is changed from cationic to anionic but retains the same framework structure. The framework consists of tubular channels with a diameter of 1.5 nm and exhibits satisfactory stability in water with a pH range of 3-11. The anionic nature of the framework allows the effective adsorption of the cationic dyes MLB, CV, and RhB with capacities of 455.6, 847.4, and 751.8 mg/g, respectively. Among them, the adsorption capacities for SCNU-Z2 on CV and RhB rank as the highest when compared with other reported MOFs. In contrast, SCNU-Z2 exhibits an extremely low capacity for anionic dyes MO and AO, making it useful for the separation of anionic and cationic dyes based on a charge-dependent mode. Interestingly, SCNU-Z2 can be used to degrade an anionic dye, MB, within 30 min under darkness at room temperature. The apparent activation energy of the dye degradation reaction is calculated to be approximately 18.96 kJ·mol-1, implying that the catalytic reaction of MB can be considered as a low-temperature thermocatalytic reaction in the dark/SCNU-Z2 system.