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CO2/H2 mixtures can be directly converted into long-chain hydrocarbons with a yield of 26.7% over a bimetallic FeCo catalyst via strengthening the reinforced chain growth reaction.

This research aims to investigate steam biomass gasification in a pilot horizontal gasifier using rubber wood pellets (RWPs) and eucalyptus wood chips (EWCs) for producing syngas with an H

The highly efficient multifunctional 3% Y–Zn0.02Zr0.02/Si-beta catalyst possessed superior butadiene selectivity and ethanol conversion in direct conversion of aqueous ethanol into butadiene.

Ethanol, as one of the important bulk chemicals, is widely used in modern society. It can be produced by fermentation of sugar, petroleum refining, or conversion of syngas (CO/H

The design and construction of advanced functional structures for photocatalysts has been proven to be an extremely effective approach to greatly enhance their properties toward higher solar-driven water splitting efficiency. Here, three ZnCdS derivatives with photocatalytic performance and structure differences are constructed through C6CoK3N6 inducing and NH3·H2O etching. And the three derivatives present huge gap in structure. In comparison with ZnCdS bulk, both flake-bulk ZnCdS cage and hollow ZnCdS particle cage exhibit specific surface area about three times larger than it. Interestingly, their optical properties and band structures showcase clearly visible difference, and their band structures display a stepped distribution. These nother expressions in structure-performance strongly reflect that chemical compositions, structural traits, and the electronic properties of the Prussian blue (PB) and its analog (PBA) materials can be tailored by external stimulus. More importantly, NH3·H2O etched hollow ZnCdS particle cage by removing Co species exhibits more excellent photocatalytic hydrogen evolution activities compared with other two derivatives, and the hydrogen evolution rate reached approximately 23 mmol•g-1 h-1 under 300 W Xenon lamp irradiation with a light power of about 514 mW•cm-2. The improved photocatalytic performances mainly depend on these advantages that enriched active sites, shortened charge-migration distance, enlarged surface area, derived more charge transfer channels, and reduced reaction overpotential.

In2O3 hollow hexagonal prisms are combined with CdS–MoS2 dumbbell electrostatic self-assembly to weaken the surface oxidation kinetics. MoS2 promotes the CdS–In2O3 S-scheme heterojunction photocatalyst to show significant photocatalytic performance.

Prussian blue analogs (PBAs) are the oldest artificial cyanide-based coordination polymers similar to metal–organic frameworks (MOFs) in structure, composition, and physicochemical properties.

Directly converting CO2 into carbon-based fuels is an alternative route to produce valuable fuels.

As a part of photocatalytic water splitting, the design of low-cost, high-activity catalysts plays an essential role in the development of photocatalytic water splitting. Metal oxides have the advantages of a wide range of sources, many varieties, and easy preparation. Doping engineering on their surface can construct new active sites and adjust their catalytic activity. In this work, a new strategy was developed through anion hybridization to regulate electron delocalization. Using one of the cobalt-based zeolitic imidazole skeletons (ZIF-67) as a precursor material, a two-step calcination method was used to prepare a P-doped Co3O4 mixed anion composite photocatalyst. The hydrogen production rate of P@Co3O4 is 39 times that of ZIF-67 and 6.8 times that of Co3O4. Through density functional theory (DFT) calculations, the electron delocalization state of the sample surface is predicted and the reaction energy barrier is reduced to promote the process of the hydrogen evolution reaction (HER). The special O(δ-)-Co(δ+)-P(δ-) surface bonding state promotes the bridging of isolated electronic states and provides active sites for the adsorption and activation of reaction substrates. The improved electron transport pathway and the synergy between the catalytic sites under the high electron transport rate are the main reasons for the enhanced photocatalytic hydrogen evolution activity. This strategy, including changing the surface bond state and optimizing the structure and composition of the catalyst not only provides a new method for preparing other MOF-derived nanomaterials with porous structures but also inspires the reasonable development of other MOF-based advanced photocatalysts.

The Fischer-Tropsch (FT) synthesis, as an alternative route to produce high-quality liquid fuels and chemicals, has received considerable attention in recent years. In this work, a nano-sized capsule catalyst (ZrO2@FeCu) with ZrO2 as a core and FeCu bimetallic oxide as a shell was fabricated by urea hydrolysis method. For comparison, FeCu@ZrO2 capsule catalyst was synthesized by the sequential precipitation method. FeCu + ZrO2 reference catalyst was obtained by physically mixing of FeCu and ZrO2 samples. Besides, these catalysts with potassium (K) modification were realized by wetness impregnation method, and the catalysts are denoted as ZrO2@FeCu-K, FeCu@ZrO2-K, and FeCu + ZrO2-K, respectively. The structure-function relationship of the obtained catalysts was systematically clarified by means of a series of characterization techniques, such as BET, XRD, H2-TPR, CO-TPD, XPS, SEM and EDS mapping. Among these catalysts after reduction, ZrO2@FeCu-K exhibited the most excellent catalytic performance with 97 % CO conversion and 49 % α-olefins selectivity by promoted CO adsorption.

Catalytic conversion of CO

Up to now, the member of zeolite family has expanded to more than 230. However, only little part of them have been reported as catalysts used in reactions. Discovering potential zeolites for reactions is significantly important, especially in industrial applications. A carbonylation zeolite catalyst Al-RUB-41 has special morphology and channel orientation. The 8-MR channel of Al-RUB-41 is just perpendicular to its thin sheet, making a very short mass-transfer distance along 8-MR. This specific nature endows Al-RUB-41 with efficient catalytic ability to dimethyl ether carbonylation reaction with beyond 95% methyl acetate selectivity. Compared with the most widely accepted carbonylation zeolite catalysts, Al-RUB-41 behaves a much better catalytic stability than H-MOR and a greatly enhanced catalytic activity than H-ZSM-35. A space-confined deactivation mechanism over Al-RUB-41 is proposed. By erasing the acid sites on outer surface, Al-RUB-41@SiO2 catalyst achieves a long-time and high-efficiency activity without any deactivation trend.

Light olefins (C2–C4) are fundamental building blocks for the manufacture of polymers, chemical intermediates, and solvents. In this work, we realized a composite catalyst, comprising MnxZry oxides and SAPO-34 zeolite, which can convert syngas (CO + H2) into light olefins. MnxZry oxide catalysts with different Mn/Zr molar ratios were facilely prepared using the coprecipitation method prior to physical mixing with SAPO-34 zeolite. The redox properties, surface morphology, electronic state, crystal structure, and chemical elemental composition of the catalysts were examined using H2-TPR, SEM, XPS, XRD, and EDS techniques, respectively. Tandem reactions involved activation of CO and subsequent hydrogenation over the metal oxide catalyst, producing methanol and dimethyl ether as the main reaction intermediates, which then migrated onto SAPO-34 zeolite for light olefins synthesis. Effects of temperature, pressure and reactant gas flow rate on CO conversion and light olefins selectivity were investigated in detail. The Mn1Zr2/SAPO-34 catalyst (Mn/Zr ratio of 1:2) attained a CO conversion of 10.8% and light olefins selectivity of 60.7%, at an optimized temperature, pressure and GHSV of 380 °C, 3 MPa and 3000 h−1 respectively. These findings open avenues to exploit other metal oxides with CO activation capabilities for a more efficient syngas conversion and product selectivity.

The effects of crystallite size on the physicochemical properties and surface defects of pure monoclinic ZrO2 catalysts for isobutene synthesis were studied. We prepared a series of monoclinic ZrO2 catalysts with different crystallite size by changing calcination temperature and evaluated their catalytic performance for isobutene synthesis from syngas. ZrO2 with small crystalline size showed higher CO conversion and isobutene selectivity, while samples with large crystalline size preferred to form dimethyl ether (DME) instead of hydrocarbons, much less to isobutene. Oxygen defects (ODefects) analyzed by X-ray photoelectron spectroscopy (XPS) provided evidence that more ODefects occupied on the surface of ZrO2 catalysts with smaller crystalline size. Electron paramagnetic resonance (EPR) and ultraviolet–visible diffuse reflectance (UV–vis DRS) confirmed the presence of high concentration of surface defects and Zr3+ on m-ZrO2-5.9 sample, respectively. In situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) analysis indicated that the adsorption strength of formed formate species on catalyst reduced as the crystalline size decreased. These results suggested that surface defects were responsible for CO activation and further influenced the adsorption strength of surface species, and thus the products distribution changed. This study provides an in-depth insight for active sites regulation of ZrO2 catalyst in CO hydrogenation reaction.

Converting syngas into ethanol (EtOH) is highly attractive but remains challenge. Dimethyl ether (DME) carbonylation with CO to methyl acetate (MA) on zeolite and its further hydrogenation to EtOH on Cu-based catalyst open a new EtOH synthesis route from syngas. In this work, a nano-sized ZSM-35 (NZ35) zeolite, possessing abundant active sites and porosity and short diffusion path, is found to realize much better activity of DME to MA than that of the conventional ZSM-35 zeolite (CZ35). In addition, a simple formic-acid-assisted solid-state method is employed for preparation an auto-reduced CuZnAl (CZAargon) catalyst under argon atmosphere. The prepared CZAargon catalyst exhibits an excellent catalytic activity for conversion of produced MA to EtOH. By investigating the effects of different integration manners of NZ35 zeolite and CZAargon catalyst, we find that EtOH can be synthesized only when the NZ35 zeolite and CZAargon catalyst pack in a dual-catalyst bed reactor. After optimizing the reaction conditions for EtOH synthesis with the combination of NZ35 zeolite and CZAargon catalyst, it is found that the DME conversion and MA selectivity are stabilized at 47.0 % and 45.6 % respectively, at 220 °C and 2.5 MPa.

Various dealuminum methods of zeolite Beta to generate the jet fuels by converting isobutyl alcohol has been investigated in detail. And related factors of the zeolite catalyst such as acid site, pore structure, and pore size which can influence reactive activity, were also studied utilizing XRD, SEM, XRF, Nitrogen adsorption-desorption, NH3-TPD, Py-FTIR, and 27Al solid-state NMR. Removal of extra-framework aluminum or part of framework aluminum by hydrochloric acid dealumination, is able to improve the diffusion property of the products in the channel of zeolite Beta via increasing the ratio of Lewis/Bronsted. Consequently, isobutyl alcohol can be quantitatively oligomerized over dealuminated zeolite Beta with the selectivity of C8−16 exceeding 50 % at a conversion of 98 %. Moreover, the deactivated catalyst can be easily regenerated by calcining it in flowing air. High conversion, high jet fuels selectivity, and facile regeneration make it an attractive potential catalyst for isobutyl alcohol oligomerization reaction.

Due to the complexity of the structure and surface property of metal oxide catalysts, hydrophobization of metal oxide catalysts is a great challenge. The hydrophobization strategy and effects of hy...

Syngas conversion can play a vital role in providing energy and chemical supplies while meeting environmental requirements as the world gradually shifts toward a net-zero. While prospects of this process cannot be doubted, there is a lingering challenge in distinct product selectivity over the bulk transitional metal catalysts. To advance research in this respect, composite catalysts comprising traditional metal catalysts and zeolites have been deployed to distinct product selectivity while suppressing side reactions. Zeolites are common but highly efficient materials used in the chemical industry for hydroprocessing. Combining the advantages of zeolites and some transition metal catalysts has promoted the catalytic production of various hydrocarbons (e.g., light olefins, aromatics, and liquid fuels) and oxygenates (e.g., methanol, dimethyl ether, formic acid, and higher alcohols) from syngas. In this outlook, a thorough revelation on recent progress in syngas conversion to various products over metal-zeolite composite catalysts is validated. The strategies adopted to couple the metal species and zeolite material into a composite as well as the consequential morphologies for specific product selectivity are highlighted. The key zeolite descriptors that influence catalytic performance, such as framework topologies, proximity and confinement effects, acidities and cations, pore systems, and particle sizes are discussed to provide a deep understanding of the significance of zeolites in syngas conversion. Finally, an outlook regarding challenges and opportunities for syngas conversion using zeolite-based catalysts to meet emerging energy and environmental demands is also presented.

The non-petroleum synthesis route of ethanol from syngas (H

To selectively transform LPG (liquefied petroleum gas), composite HZSM-5/SAPO-5 zeolite catalysts were fabricated with an adjustable Bronsted acid/Lewis acid (BA/LA) ratio and a weak acid/strong acid (WA/SA) ratio. HZSM-5 powder (SiO2/Al2O3 = 100) and SAPO-5 synthetic gel (SiO2/Al2O3 = 0.2) were employed as the starting materials. Adopting a gel/solid weight ratio of 20 mL g−1 and a crystallization temperature of 180 °C, the synthetic HZSM-5/SAPO-5-20–6 h catalyst showed a BA/LA ratio of 3.25 and a WA/SA ratio of 1.47, and during the conversion of LPG, the propylene and ethylene selectivity and the P/E ratio reached 72.22%, 62.56%, and 1.39, respectively, in a 600 °C fixed bed gas-phase reaction and a W/F value of 15 g h mol−1 was obtained. As the crystallization time was extended to 24 h, the BA/LA ratio became 2.83, and the propylene and ethylene selectivity increased to 68.50% while the selectivity for C5+ HCs and CH4 was reduced to 14.88% and 8.59%, respectively.

The direct synthesis of iso-butanol is an important reaction in syngas (composed of CO and H2) conversion. K–ZnO/ZnCr2O4 (K–ZnCr) is a commonly used catalyst. Here, Ga3+ is used as an effective promoter to boost the efficiency of the catalyst and retard the production of CO2. X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflection spectroscopy and electron microscopy were used to characterize the structural variations with different amounts of Ga3+, the results showed that the particle size of the catalyst decreases with the addition of Ga3+. The temperature-programmed desorption of NH3 and CO2, and diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTs) analysis of the CO adsorption revealed that the acidity and basicity were altered owing to the different forms of Ga3+ adoption. X-ray photoelectron spectroscopy and density functional theory (DFT) calculations revealed that the formation of Ga clusters that are coordinated on the exposed surfaces of ZnCr2O4, and undergo a tetra-coordinated Ga3+ exchange with one of the Zn in ZnCr2O4 (ZG) and ZnGa2O4, probably depends on the amount of Ga added. The structural evolution of the Ga3+ promoted K–ZnO/ZnCr2O4 catalysts can be described as follows: (i) the main forms are ZG and Ga coordinated ZnCr2O4, in which the amount of Ga3+ is below 1.10 wt%; and (ii) the Ga3+ containing compound is gradually changed from ZG to ZnGa2O4 and the amount of gallium clusters increased when the amount of Ga3+ was higher than 1.10 wt%. The catalytic performance evaluation results show that K–Ga1.10ZnCr exhibits the highest space time yield and selectivity of alcohols, in which the three compounds play different roles in syngas conversion: ZG is the main active site that boosts the efficiency of the catalysts, owing to the intensified CO adsorption and decreased activation energy of CHO formation through CO hydrogenation; ZnGa2O4 only modifies the surface basicity and acidity on the catalyst, thereby impacting the carbon chain growth after the CO is adsorbed. The effects of Ga coordinated with ZnCr2O4 shows little impact on the CO adsorption owing to the weak electron donating effects of Ga.

Functionalized catalysts with multiple active centers have been studied in direct conversion of ethanol to butadiene (ETB). However, it is still a considerable challenge to control the synergistic effect of multiple active centers. Here, we report that a series of ZnMg/SBA-15-based catalysts were synthesized for the direct ETB process. The non-polar solvent n-hexane is utilized to improve the synergistic effects of ZnO, MgO and SBA-15. The characterization results demonstrate that the ZnMg/SBA-15-hexane catalyst, prepared from n-hexane solvent, can increase dehydrogenation activity and promote synergistic catalysis. The direct ETB performance reveals that it exhibits an excellent selectivity of 70% towards the butadiene product. Further, our in situ DRIFTS analysis indicates that aldol condensation and the MPV reaction are the rate-determining steps of the direct ETB process. The present work offers a simple strategy to optimize synergies of multiple active centers.

Even though the transformation of syngas into aromatics has been realized via a methanol-mediated tandem process, the low product yield is still the bottleneck, limiting the industrial application of this technology. Herein, a tailor-made zeolite capsule catalyst with Ga doping and SiO2 coating was combined with the methanol synthesis catalyst Cr2O3 to boost the synthesis of value-added aromatics, especially para-xylene, from syngas. Multiple characterization studies, control experiments, and density functional theory (DFT) calculation results clarified that Ga doped zeolites with strong CO adsorption capability facilitated the transformation of the reaction intermediate methanol by optimizing the first C–C coupling step under a high-pressure CO atmosphere, thereby driving the reaction forward for aromatics synthesis. This work not only reveals the synergistic catalytic network in the tandem process but also sheds new light on principles for the rational design of a catalyst in terms of oriented conversion of syngas., The single-pass conversion of syngas into para-xylene was realized using a bifunctional catalyst Cr2O3/Ga-ZSM-5@SiO2. The Ga species facilitates the methanol consumption process by C–C coupling optimization, enhancing the yield of the target aromatics.

An oxide-zeolite (ZnCr2 O4 -ZSM-5) catalyst for directly converting CO2 to aromatics was designed and developed. It showed high PX/X (the C-mol ratio of p-xylene to all xylene) and PX/aromatics (the C-mol ratio of p-xylene to aromatics) ratios, which reached 97.3 and 63.9 %, respectively.

As one of the Holy Grail reactions in C1 chemistry, direct selective oxidation of methane to methanol under mild and non-harsh conditions remains a big challenge. Hydroperoxide (H2O2), as a primary oxidant, applied widely in the low-temperature direct selective conversion of methane to methanol. Moreover, the hydrogen and oxygen mixture gas achieves better reaction activity and higher methanol selectivity than H2O2 when using palladium-gold (Pd-Au) bimetallic nanoparticles as the catalyst. In this paper, we studied the key roles of the physical and chemical characteristics of Pd-Au nanoparticles in this direct selective oxidation reaction with hydrogen and oxygen as the oxidant at 50 °C. Au metal shows an indispensable role in direct methane to methanol process in this study. High methanol productivity and selectivity are achieved when Au of 0.5–2.5% is added into the carbon nanotubes (CNTs) supported Pd catalyst. Moreover, the loading amount of Pd-Au nanoparticles also affect the methane activation ability and the methanol selectivity obviously. Much more active and stable Pd-Au nanoparticles are generated in CNTs supported 2.5% Pd-2.5% Au nanoparticles catalyst than those in lower metal content catalysts. In addition, the Pd bivalent state is proved to be the most active content in the Pd-Au nanoparticles catalyst, achieving much higher methanol selectivity and productivity when compared to Pd metallic state. For further clarifying the physical and chemical characteristics of catalysts, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Hydrogen-Temperature-programmed reduction (H2-TPR), and CO pulse adsorption measurement (CO-PULSE) analysis methods are also measured.

Keen interest is taken in zeolite-encapsulated metal nanoparticles (NPs) owing to their excellent performance and ultrastability in heterogeneous catalysis. Herein, we propose a simple and efficien...

Direct synthesis of dimethyl ether (DME) from syngas can be realized over mixing methanol synthesis catalyst and methanol dehydration catalyst. Different with the general studies on mixture catalys...