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Direct synthesis of aromatics from syngas provides a promising approach for the production of fine chemicals from non-petroleum carbon resources. In this study, direct conversion of syngas into aromatics was investigated over a serial of bifunctional catalysts coupling ZnCrO x oxides and H-ZSM-5 zeolites with different morphologies. Detailed investigation showed that the CO conversion was positively correlated with the Brønsted acid sites, and the differences in aromatics selectivity and aromatics distribution on different bifunctional catalysts with different morphologies of H-ZSM-5 zeolites were attributed to the synergistic effects of acidity and particle size. For nano-type zeolites, changes in acidity might not have a significant effect on aromatics selectivity, while the transfer of intermediate species on coffin-type zeolites was mainly influenced by acidity. Moreover, for different morphology zeolites of nano-type n-Z5-125 and coffin-type c-Z5-100 with similar acidity, the side reactions in syngas aromatization on the former were 1.7 times higher than those on the latter. The reactants diffused more readily on TPAOH treated c-Z5-150-0.1 M, which promoted olefins cyclization and further increased the aromatics selectivity from 69.8% to 74.8%. [Display omitted] • The CO conversion in STA is positively correlated with the Brønsted acid sites. • H-ZSM-5 with external framework Al and short b-axis easily forms C 8 + aromatics. • TPAOH-treated c-Z5-150 zeolite is effective in enhancing the aromatics selectivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrathin CuCoAl nanosheets were synthesized by AMOST strategy. • The ultrathin CuCoAl nanosheets exhibited excellent ethanol selectivity. • The formation of CH x derived from CO dissociation and formate hydrodeoxygenation. • A triply synergetic catalysis of Cu+, Co and –OH promoted the synthesis of ethanol. Ultrathin CuCoAl nanosheets derived from layered double hydroxide (LDH) precursor (1–3 cationic-layers) were successfully synthesized by aqueous miscible organic solvent treatment (AMOST) strategy and performed for ethanol and higher alcohols production via CO hydrogenation. The ultrathin CuCoAl nanosheets (CuCo-LDH-aw) demonstrated a comparatively higher total alcohols (ROH) selectivity of 47.6 %, and the molar fraction of ethanol reached up to 37.5 % among the total alcohols. As revealed by XRD, TEM, SEM, BET and AFM characterizations, the uniform dispersion of CuCo NPs was observed over the ultrathin CuCoAl nanosheets. Moreover, the optimum ultrathin CuCoAl nanosheets exhibited a higher ratio of Cu+/(Cu0 + Cu+), which exerted a positive role on non-dissociative CO* insertion CH x intermediates. More significantly, XPS and in situ CO-DRIFT techniques uncovered the formation of CH x intermediates derived from bridge CO dissociation on the metallic Co species and the formate hydrodeoxygenation route, which involved CO* and surface hydroxyl groups (–OH) reaction. Consequently, it was concluded that the triply synergistic effect of Cu+, Co and surface hydroxyl groups (–OH) species contributed to the improvement in ethanol selectivity via CO hydrogenation. [ABSTRACT FROM AUTHOR]

Herein, we report the performance of the catalytic combustion of methane over the Ce-doped SnO 2 catalysts. Doping with Ce increases the surface areas, decreases the crystallite sizes, and activates both the surface metal cations and surface oxygen species. Upon methane combustion, the surface Sn 4+ cations are active sites, and the surface lattice oxygen plays an important role, as well. Kinetics results suggest that the activation energy ( E a ) and pre-exponential factor ( A ) are determined by the reducibility and the area-specific quantity of the surface Sn 4+ cations, respectively. The Sn 0.7 Ce 0.3 O 2 catalyst exhibits the highest area-specific rate because of its lowest E a and relatively bigger A values. Its turnover frequency is five times higher, as compared with the SnO 2 . The reaction pathways upon the Sn-rich catalysts (SnO 2 phase) follow the Mars–van Krevelen model, while they become more complex upon the Ce-rich ones (CeO 2 phase). Additionally, these SnO 2 -based catalysts display the high water resistance. [ABSTRACT FROM AUTHOR]

This report demonstrated the iso -butanol direct synthesis from syngas over varied alkali metals modified Cr/ZnO catalyst. The Cr/ZnO catalyst was prepared by a general co-precipitation method and then modified with varied alkali metals: Li, Na, K and Cs. The prepared alkali metals modified catalysts, Cr/ZnO–Li, Cr/ZnO–Na, Cr/ZnO–K and Cr/ZnO–Cs, were evaluated by the reaction of iso -butanal direct synthesis from syngas. Among these catalysts, the K modified catalyst Cr/ZnO–K exhibited excellent catalytic ability on iso -butanol synthesis. The CO conversion obtained on this Cr/ZnO–K catalyst reached up to 27.39%, with the highest iso -butanol selectivity of 15.58%. We also investigated the effect of different Li precursors, Li 2 CO 3 and LiOH, on the catalytic performance of Cr/ZnO catalyst, and the reaction results indicated that the LiOH precursor modified catalyst Cr/ZnO–Li–OH had better catalytic performance. All the catalysts were characterized by BET, XRD, H 2 -TPR, SEM–EDS and TG–DTA to further disclose the function of alkali metals to Cr/ZnO catalyst in iso -butanol synthesis. We found that the reducibility of the active phase of non-stoichiometric spinel Zn x Cr 2/3(1 −x ) O, the crucial species for iso -butanol synthesis, was significantly influenced by alkali metals modification, which consequently determined in the diverse catalytic performance of alkali metals modified catalysts for iso -butanol synthesis. [ABSTRACT FROM AUTHOR]

A series of Zn–Cr oxides nanoparticles with different degrees of cation disorder distribution were obtained by a coprecipitation and postcalcined method. Some qualitative analysis, such as Transmission Electron Microscope (TEM), Powder X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used to confirm the structure of Zn–Cr oxides and the existence of cation disorder distribution. Meanwhile, the Rietveld method was used to quantitatively investigate the changes of cation distribution between tetrahedral and octahedral vacancies of different catalysts. The results demonstrated that the degree of cation disorder distribution became higher with decreasing annealing temperature and increasing the molar ratio of Zn–Cr. Furthermore, the level of cation disorder distribution in Zn–Cr spinel structure affects tremendously both texture parameters and acid–base properties of catalysts which make isobutanol generation more effectively. Most importantly, we first discover that the isobutanol productivity presents approximately linear relationship to the level of cation disorder distribution of Zn–Cr spinel in quantitatively, unambiguously revealing the structure–activity relationship between the activity of isobutanol and the structure of Zn–Cr spinel. [ABSTRACT FROM AUTHOR]

A series of mesoporous amorphous Ni–ZrO 2 composite oxides with varying Ni contents were prepared by an improved co-precipitation/reflux digestion method and evaluated in the dry reforming of methane. The synthesis method enabled the preparation of uniformly sized Ni particles evenly dispersed within the porous amorphous zirconia matrix. The catalytic reaction results showed that mesoporous amorphous Ni–ZrO 2 -CR-15 catalyst (Ni loading of 15 wt%) exhibited the highest catalytic activity and excellent stability during the 80-h test among other studied Ni–ZrO 2 catalysts. Rapid decline in the catalytic activity was observed for catalysts prepared by traditional impregnation and co-precipitation methods. The improved catalytic performance was attributed to the homogeneous distribution of the small Ni nanoparticles because of the high surface area of the amorphous structure and the strong interaction between Ni and ZrO 2 . Additionally, the confinement effect of the nano-amorphous structure was responsible for the superior thermal stability of the Ni nanoparticles. Furthermore, Ni–ZrO 2 -CR-15 catalyst displayed high resistance against carbon deposition owing to the presence of multiple interfaces between the metal and oxide support, absence of strong Lewis acid sites, and presence of different active centers for CO 2 dissociation. [ABSTRACT FROM AUTHOR]

[Display omitted] • An appropriate amount of CTAB enhances the dispersion of metal particles. • CTAB significantly affects the electronic structure of Cu and Co species. • The synergistic effect between Cu+-Co0 site promotes the formation of ethanol. • CuCo-0.10C/(Si) exhibits the highest ethanol selectivity. We explored herein the feasibility of using surfactant-assisted CuCo catalysts for the synthesis of ethanol by CO hydrogenation. Combined characterization results demonstrated that surfactant CTAB can significantly inhibited the aggregation and retarded the deep reduction of Cu and Co species, which was crucial to obtaining highly dispersed metal particles and the optimal electronic environment of Cu and Co species. A strong synergistic effect occurred at the interface of Cu+-Co0 species in intimate contact on bimetallic CuCo-0.10C/(Si) catalyst, have evidenced to be responsible for efficiently conversion of CO to ethanol by integrating the CO* and CH x * intermediates depend on the classical insertion mechanism. The optimal bimetallic CuCo-0.10C/(Si) catalyst with an enhanced ethanol selectivity of 33.4 wt% at a superior CO conversion of 32.0%, achieving the highest space-time-yield toward total alcohols of 52.0 mg/mL cat ·h and ROH selectivity (21.5%), thus presenting a critic step to guide the rational design of CuCo-based catalysts for ethanol synthesis in CO hydrogenation process. [ABSTRACT FROM AUTHOR]

[Display omitted] • NASICON was used for acrylic acid production from formaldehyde and acetic acid. • Acrylic acid + methyl acrylate selectivity of 71% was successfully achieved. • Catalyst properties and structure–activity relationship has been explored in-depth. • Medium-strong basic and acid sites with moderate amount account for AA formation. The development of environmentally friendly and efficient catalysts for the production of essential chemicals has always been a desirable goal for technology in the chemical industry. In this paper, we fabricated a kind of sodium (Na) super ionic conductor (NASICON)-type materials (H 1-x Ti 2 (PO 4) 3-x (SO 4) x) with different Ti/P ratios through tuning titanium content in synthetic mother liquor, and applied them to the aldol condensation reaction of acetic acid (HAc) and formaldehyde (FA) to acrylic acid (AA) and methyl acrylate (MA), which has never been not reported in previous researches. More importantly, these novel catalysts have showed their tremendous potential at the efficiency of AA + MA production, and over an optimized catalyst of NSC-Ti/P-0.53, the AA + MA selectivity being 71% (HAc input-based) was achieved at 360 ℃ when the reactant with FA/HAc molar ratio of 5:1 was fed; whereas, a highest space–time-yield (STY) of target products (∼37.2 μmol·g−1·min−1) was obtained with the FA/HAc molar ratio of 1:2.5, which is comparable to the best result reported previously. The detailed analysis of characterizations demonstrated that the change in the Ti/P ratio in the series NASICON catalysts led to the variation in the phase composition, the textural properties, surface titanium oxidation state, etc. thereby tuning the surface acid-base property, which is quite important for the present condensation reaction. More amounts of acidic sites and basic sites as well as their moderate distribution were proved to exert the promotional effects on the formation of AA and MA. [ABSTRACT FROM AUTHOR]

[Display omitted] • Z0.8C/Z5 is effective for the one-step aromatization process from syngas. • The non-stoichiometric spinel brings more amorphous ZnO and oxygen vacancies. • The presence of ZnO and oxygen vacancies together pull the CO conversion. Bifunctional catalysts composed of ZnCrO x oxide and ZSM-5 were widely used in syngas-to-aromatics (STA). The CO conversion on bifunctional catalysts was generally higher than that on oxide catalysts attributed to the pulling effect of zeolite, but the key factor for the improvement of CO conversion was still short of systematical explanation. In this work, the degree of nonstoichiometric spinel of ZnCrO x (ZxC) oxides was finely tuned through modulating the ratio of Zn/Cr, which could significantly influence the catalytic behaviors of ZnCrO x /ZSM-5 catalysts for the CO hydrogenation to aromatics. The increase of nonstoichiometric spinel corresponded to the increase of oxygen vacancies and the enhancement of Zn-Cr synergistic effect, which promoted the activation of H 2 and CO, leading to a dramatic increase of CO conversion. The work revealed that the action of ZnO and oxygen vacancies was the key factor for CO pulling in ZnCrO x oxide and ZSM-5 catalyzed STA reaction. [ABSTRACT FROM AUTHOR]

• FeNa/ZrO 2 show higher C 2 -C 7 olefin selectivity compared to SiO 2 , Al 2 O 3 and CNT. • C 2 -C 7 olefin yield of reached 111.4 g Kg cat -1h−1 on FeNa/ZrO 2 with O/P = 8. • The content of Fe 5 C 2 can be regulated by the support with carbon rich surface. • Higher ratio of C/H on the surface inhibit the hydrogenation of olefins. Catalytic utilizing of CO 2 into valuable olefins on Fe-based catalysts is a feasible way to mitigate the pressure of carbon neutrality. Herein, by investigating the effects of support (SiO 2 , Al 2 O 3 , CNT, and ZrO 2) on the structure and catalytic performance of iron catalysts, we have found that ZrO 2 supported catalysts are more beneficial to olefin selectivity and chain growth. The optimization catalytic performance of FeNa/ZrO 2 displays C 2 -C 7 olefin selectivity of 68.2% (O/P = 8.0) with a space time yields (111.4 g Kg cat -1h−1) at X CO2 = 32.7%, 320 ⁰C, 2.0 MPa, CO 2 /H 2 /Ar = 1:3:3, and 9000 mL g-1h−1. Characterizations show that the support regulates the composition of the iron oxide phase and the iron carbide phase and induces to form the highest content of Fe 5 C 2 on the spent FeNa/ZrO 2 , which is probably caused by the carbon rich surface and lower disorder of carbon species. Besides, the higher intensity of CO 2 and CO adsorption and lower intensity of H 2 adsorption is confirmed on the surface of the FeNa/ZrO 2 catalysts, leading to a higher ratio of C/H on the surface of the spent catalysts and consequently inhibiting the hydrogenation of olefins. Therefore, the O/P is 8 times as many as that on the FeNa/SiO 2 and FeNa/Al 2 O 3. Understanding the effect of support on CO 2 hydrogenation to olefins over iron-based catalysts would be significant for precisely designing new catalysts. [ABSTRACT FROM AUTHOR]

A series of K–Cu/ZrO 2 catalysts with different La loadings for isobutanol synthesis from CO hydrogenation were prepared by a co-precipitation method. The catalysts were characterized by XRD, reactive N 2 O adsorption, XPS, H 2 -TPR, in situ IR and Raman techniques, and then tested for isobutanol synthesis from CO hydrogenation at the conditions of 360 °C, 10.0 MPa, GHSV = 3000 h −1 and H 2 /CO = 2.5. These characterization results showed that incorporation of La into the K/Cu–Zr catalyst resulted in increase of BET surface area and dispersion of catalyst particles. Especially, medium La addition facilitated the synergistic effect between Cu–Zr interactions, improved the reducibility of catalyst and increased the amounts of dispersed copper. An enrichment of C1 intermediates on catalyst surface related to high dispersed CuO is better for chain growth. In the isobutanol synthesis reaction, the conversion of CO and selectivity of isobutanol increased first and then decreased as the increase of La concentration. Among these La-promoted K/Cu–Zr catalysts, the 3% La/Cu/Zr catalyst exhibited the highest alcohol selectivity of 32.8 wt%, which can be radically attributed to the highest Cu surface area. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two types of catalysts were prepared by impregnation (IP) and impregnation coprecipitation (ICP) methods. [•] ICP catalyst showed better performance of methanation than that of IP catalyst in slurry reactor. [•] ICP method is favor for the formation of small size Ni particles and more reducible NiO. [•] Zr doping can moderate the interaction between Ni and γ-Al2O3 support and promote the dispersion of Ni. [Copyright &y& Elsevier]

[Display omitted] • Highly dispersed La 2 O 3 preferentially enhances the dispersion of Cu rather than Co. • La 2 O 3 significantly affects the electronic structure of Cu and Co species. • The synergistic effect between Cu+-Co0 site promotes the formation of ethanol. • CuCo/(5La/Si) shows the highest ethanol selectivity. The specific synthesis of ethanol from syngas is particularly important for C1 chemistry platforms. Herein, the uniformly decorated xLa/SiO 2 -supported CuCo catalysts were prepared by a facile incipient wetness impregnation (IM) method. On the basis of detailed characterization and catalytic performance, the relationship between the distribution of active Cu and Co species and intrinsic catalytic activity was established and discussed. The La 2 O 3 preferentially enhances the dispersion of copper and inclines to generate stable Cu+ from Cu-O-La units. Additionally, SiO 2 is conducive to the generation of Cu0, and then promotes the reduction of adjacent Co2+ to Co0 through hydrogen spillover. It was found that the CuCo/(5La/Si) catalyst showed a highest CO conversion of 44.2% and the space time yield of total alcohols (STY ROH) of 61.6 mg/mL cat ·h, which was 8.0-fold and 3.3-fold higher than that of undecorated CuCo/(Si) catalyst, respectively. Moreover, a superior ethanol selectivity in total alcohols is as high as 34.0 wt%. The significant improvement in catalytic performance is attributed to the abundant Cu+-Co0 in the interface with strong capacity on C–C chain growth. This work provides a novel and simple model for the rational design other related CuCo catalyst with beneficial performance, which is of great significance to reveal the unique synergistic interface between Cu and Co species. [ABSTRACT FROM AUTHOR]

Abstract: The Cu x –Zn y –O (Cu:Zn= x:y) mixed oxide catalysts with different Cu:Zn atomic ratio were prepared through a new solid-state reaction method. The physicochemical properties of these catalysts were characterized by thermal analysis (TG-DTA), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), N2 adsorption and H2 temperature programmed reduction (H2-TPR). The results showed that with the increase of the molar ratio of Cu:Zn, the crystallite sizes decreased at first and then increased. The smallest crystallite size was realized when the molar ratio of Cu:Zn was 4:6. At the same time, the largest surface area was also obtained at this molar ratio. The catalytic performances of Cu x –Zn y –O mixed oxide to hydrogenation of methyl acetate were tested using flow-type fixed bed reactor. The conversion of the Cu0.4–Zn0.6–O catalyst to methyl acetate was 72.6%, higher than those of Cu x –Zn y –O catalysts with other molar ratios. The highest catalytic activity of the Cu0.4–Zn0.6–O catalyst was due to its smaller crystallite size, larger surface area and higher particles dispersion compared with the other samples. Furthermore, Cu0.4–Zn0.6–O catalyst was tested in dual-catalyst-bed reactor to synthesize ethanol from dimethyl ether (DME) and syngas (CO+H2) with the coexisting zeolite catalyst. For comparison, the Cu–Zn–O catalyst prepared by the conventional co-precipitation method was also tested as a reference catalyst. The reaction results showed that the conversion of Cu0.4–Zn0.6–O catalyst to DME was higher than that of Cu–Zn–O catalyst. All in all, both the preparation method and the molar ratio of Cu–Zn are responsible for the catalytic activity of the prepared catalysts. [Copyright &y& Elsevier]

Abstract: A series of supported Co/SiO2 catalysts were prepared by surface impregnation combustion method using cobalt nitrates and citric acid, and the precursors were burnt in different atmospheres. The effects of different calcination atmospheres on the properties of the supported Co/SiO2 catalysts were systemically studied by TG-DTA, XRD, Raman spectrum, TPR, in situ FTIR, TEM, BET and H2-chemisorption techniques. The burnt catalyst Cargon-air-reduction which was first burnt in argon and then oxidized in air had about 10nm Co3O4 crystalline size, much smaller than that which was directly burnt in air (Co3O4 size: about 15nm) and that prepared by conventional impregnation method (Co3O4 size: about 32nm) using cobalt nitrate as impregnating solution. Characterizations and FTS results of two other references using different organic cobalt salt aqueous (cobalt acetate and cobalt citrate) as impregnating solution were also added in the supporting information. Comparing with our previously reported Cargon catalyst directly burnt in the argon atmosphere without further reduction, the influence from surface amorphous carbon and carbonic residues was completely eliminated. The activity of the burnt catalyst Cargon-air-reduction prepared by surface impregnation method was threefold higher than that of the reference CN-reduction prepared by conventional incipient-wetness impregnation method. The surface impregnation combustion method described herein was promising to prepare highly dispersed supported metallic catalysts with smaller particle sizes. [Copyright &y& Elsevier]

Abstract: A zeolite capsule catalyst Cr/ZnO–S–Z was prepared successfully by a novel dual-layer method, in which one layer of neutral Silicalite-1 zeolite shell was first synthesized on the bimetallic Cr/ZnO core catalyst, acting as the intermediate layer for the following H-type H-ZSM-5 zeolite shell direct synthesis on its surface. By using this dual-layer method, it can be easily realized that the formation of H-ZSM-5 zeolite membrane on the millimeter-sized bimetallic substrates. Direct synthesis of dimethyl ether (DME) from syngas at higher reaction temperature was the application of this zeolite capsule catalyst to test its catalytic performance. In reaction, this zeolite capsule catalyst could realize the exactly controlled synthesis of DME, suppressing the formation of other alkane/alkene by-products simultaneously, demonstrating its exclusive ability for the selective synthesis of target product compared with the conventional hybrid catalyst. [Copyright &y& Elsevier]

[Display omitted] • Calcination at N 2 resulted in the formation of more surface oxygen vacancies. • The formation of oxygen vacancies facilitated the un-dissociated adsorption of CO. • The C–C coupling and isobutanol producing were promoted over ZnCr-N 2 catalyst. During the synthesis of high alcohols, surface oxygen vacancies play a crucial role in CO/H 2 activity and catalytic performance. Herein, the Zn-Cr catalysts with different O species were obtained by heating the Zn-Cr catalysts in different atmospheres (N 2 , H 2 , and O 2), aiming to figure out the influences of O species in the surface structure and catalytic behavior. Using a series of characterizations (in situ DRIFTS, CO-TPD) and DFT calculation, the nature and contributions to catalyst activity of different oxygen species were confirmed for calcined ZnCr catalysts. It was found that the ZnCr catalyst calcined at an inert atmosphere exhibited more abundant oxygen vacancies and more surface hydroxyls with high activity. These two species determined the formation of non-dissociative adsorption CO and the stabilization of formate intermediate. As a result, the ZnCr-N 2 obtained remarkably improved catalytic performance. [ABSTRACT FROM AUTHOR]

Abstract: A commercial Cu-based catalyst for methanol synthesis was studied using a stirred autoclave reactor system in the present study. The synthesis reactions were conducted for different time under the same reaction conditions in order to get catalyst samples with different deactivation degrees. The composition and morphology of the catalyst samples before and after reaction were characterized by the means of temperature programmed reduction (TPR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS), elemental analysis (EA) and nitrogen adsorption techniques. The experimental results indicated that Cu composition of the catalyst had not changed significantly during the reaction, and sintering of Cu particles of the catalysts was the main cause of the catalyst deactivation with time on stream. [Copyright &y& Elsevier]

Abstract: Three kinds of H-ZSM-5 zeolite capsule catalysts were prepared by a direct hydrothermal synthesis method, where directly synthesized H-ZSM-5 membrane was coated perfectly onto Co/SiO2 catalyst pellets of different sizes. SEM, EDS and XRD were used to characterize the catalyst morphology and to identify the H-ZSM-5 structure of zeolite capsules. Surface acidity and pore property of these catalysts were tested by NH3-TPD and gas adsorption. The results showed that smaller Co/SiO2 pellets with large external surfaces were favorable for zeolite capsule growth under the same synthesis conditions. The Fischer–Tropsch synthesis (FTS) reactions using the conventional FTS catalyst Co/SiO2 or the physically mixed catalyst of Co/SiO2 with H-ZSM-5, or the zeolite capsule catalysts were each conducted. The isoparaffins were selectively obtained on the capsule catalysts and the mixed catalyst. The capsule catalysts exhibited higher selectivity of isoparaffins than the mixed catalyst due to the space-confined effect and the shape-selective effect. Especially, capsule catalysts with smaller sizes showed higher CO conversion and higher isoparaffin selectivity. Changing the substrate pellet size could control the capsule catalysts’ structure and their activity as well as their selectivity. [Copyright &y& Elsevier]

As for the 3% Ce after treated by CO 2 /H 2 , when the reducing gas atmosphere is switched from CO to H 2 , the surface ratio of Na/Fe and the ratio of Fe 3 O 4 /Fe x C decreases, the CO 2 desorption temperature and the ratio of defect oxygen increases, and the adsorbed CO 2 on the surface of iron oxides probably react with the presence of H 2 to produce the surface oxygen ions, inhibiting the conversion of CO 2 to CO and the transformation of CO to hydrocarbons. Therefore, the conversion of CO 2 decreased from 36% to 12%, the selectivity of CO increased from 11% to 65%, the FTY decreased from 1.37*10-6 mol CO2 /g Fe •s to 0.13*10-6 mol CO2 /g Fe •s and the ratio of O/P decreased from 1.7 to 0.2. [Display omitted] • CO 2 conversion, CO selectivity and FTY over FeCeNa were regulated by reducing gas. • Reducing gas atmosphere can regulate the surface ratio of Fe 3 O 4 /Fe x C y and Na/Fe. • The CO 2 desorption temperature can be tuned by reducing gas atmosphere. • The adsorbed CO 2 can be turned into surface oxygen species in the presence of H 2. In this work, a series of FeCeNa catalyst were prepared and evaluated in the reducing gas atmosphere of CO and H 2 , respectively. The catalytic performance of hydrogenation of CO 2 to olefins show the reducing gas atmosphere has an apparent effect on the CO 2 conversion, CO selectivity, FTY and the ratio of O/P. In situ XRD, in situ XPS and TPSR were further carried out to investigate the effect of reducing gas atmosphere on the performance of FeCeNa catalyst for the hydrogenation of CO 2 to olefins. When the reducing gas atmosphere of 3% Ce is switched from CO to H 2 , the catalyst has lower Fe 3 O 4 /Fe x C y , higher ratio of defect oxygen and higher CO 2 desorption temperature. The adsorbed CO 2 on the surface can react with the presence of H 2 to produce higher ratio of the surface oxygen ions, which probably occupies the surface of the catalyst and inhibits the conversion of CO 2 to CO and the transformation of CO to hydrocarbons. Besides, the surface Na/Fe ratio of 3% Ce decreases when the reducing gas atmosphere is switched from CO to H 2 , inhibiting the formation of olefins. Therefore, as for 3% Ce, switching the reducing gas atmosphere from CO to H 2 can decrease the ratio of Fe 3 O 4 /Fe x C y , increase the ratio of defect oxygen and surface oxygen ion species, decrease the ratio of Na/Fe, and increase the CO 2 desorption temperature, subsequently affect the RWGS and FT reaction, leading to the conversion of CO 2 decreasing from 36% to 12%, the selectivity of CO increasing from 11% to 65%, the FTY decreasing from 1.37*10−6 mol CO2 /g Fe •s to 0.13*10−6 mol CO2 /g Fe •s and the ratio of O/P decreasing from 1.7 to 0.2. [ABSTRACT FROM AUTHOR]

For Fe-based Fischer-Tropsch synthesis catalyst, how to decrease CO 2 formation is a big challenge. In this work, a capsule catalyst (FeMn@HZSM-5) with FeMn as core and HZSM-5 as shell was prepared and used for Fischer-Tropsch to olefins (FTO) reaction, compared with bare FeMn catalyst and several hybrid catalysts by physically mixing FeMn and HZSM-5 in different ways. Among these catalysts, the FeMn@HZSM-5 capsule catalyst showed the best catalytic performance with the highest light olefins selectivity and the lowest CO 2 selectivity. Compared with FeMn catalyst, the CO 2 selectivity of FeMn@HZSM-5 catalyst decreased more than 10%. However, the CO 2 selectivity of other physically mixing catalysts was similar to that of bare FeMn catalyst, indicating that randomly adding HZSM-5 had no effect on depressing the CO 2 formation. Benefiting from the HZSM-5 shell, the FeMn@HZSM-5 capsule catalyst could effectively affect the diffusion of H 2 O and thus suppress the water-gas shift reaction in FTO reaction. [Display omitted] • A capsule catalyst with FeMn as core and HZSM-5 as shell was used for FTO reaction. • Compared with FeMn, the CO 2 selectivity of FeMn@HZSM-5 decreased more than 10%. • The HZSM-5 shell structure suppresses the water-gas shift reaction in FTO reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe component was added for strong chain growth ability in Cu/ZrO 2 catalysts. • The addition of Fe facilitated the dispersion of CuO. • The Cu-Zr interaction was obviously improved after adding Fe component. • A selectivity of 21.7(wt)% for isobutanol and a space time yield (STY) of 202 g L cat −1h−1 for total alcohols were obtained over KFe 0.013 CuZrO 2 catalyst. Direct conversion of syngas (H 2 /CO) to isobutanol is a promising route for clean coal combustion. However, there are still many challenges in the catalyst system of isobutanol synthesis, such as low CO conversion and alcohol yield. In this paper, we introduce Fe component with strong chain increasing ability into CuZrO 2 -based catalyst to modify it, which significantly improved the CO conversion and total alcohol space–time yield (STY). The results of the characterization showed that the introduction of Fe increased the specific surface area of the catalyst, promoted the dispersion of components, and enhanced the interaction between Cu and ZrO 2. The KFe 0.013 CuZrO 2 catalyst surface possessed the most amount of weakly adsorbed CO and basic sites, which were conductive for C 2 intermediate formation and aldol-condensation reaction respectively. Thus, it exhibited a CO conversion of 48.6%, a selectivity of 21.8(wt)% and a space time yield (STY) of 202 g·L cat −1·h−1 total alcohols. [ABSTRACT FROM AUTHOR]

• The appropriate La dopant improve the formation of oxygen vacancy sites. • The introduction of La into the ZnCr catalyst promoted the formation and stability of the formate intermediate. • The doping of La promoter favored the isobutanol synthesis. A series of catalysts were designed and synthesized via doping lanthanum into ZnCr oxide to realize efficient synthesis of isobutanol from syngas. By applying a combination of characterizations (XRD, TEM, EPR, XPS and in situ FT-IR) and DFT calculations, the effects of lanthanum promoter on catalyst structure and catalytic performance were investigated. With the doping of lanthanum, ZnCrLa x composite oxides with a novel catalyst structure were constructed, in which Zn atom at tetrahedron site was partly substituted by doping La atom. The presence of this structure enhanced the formation of more oxygen vacancy sites and further benefitted the CO activation. In addition, formate intermediate was easier to generate and exhibited superior stability over ZnCrLa x surface thus leaded to remarkably promoted catalytic activity. The ZnCrLa 0.05 catalyst achieved optimum total alcohols selectivity of 61%, and the fraction of isobutanol reached as high as 24.6% under CO conversion of 23%. [ABSTRACT FROM AUTHOR]

• Silylated Ga/Z5 catalysts were used in propane dehydroaromatization. • An appropriate SiO 2 content on external surface was beneficial to cover strong BAS. • Sufficient weak acid was vital to propane dehydroaromatization. • The undesired cracking reaction was successfully depressed on the external surface. • Extended duration of CLD process narrowed the micropore mouth size of Ga/Z5. Dehydroaromatization of propane to high value-added aromatics, especially benzene, toluene and xylene (BTX), has attracted widespread attention. Many works have been done to improve the catalytic performance of gallium loaded HZSM-5 catalysts. However, there were few reports focused on reducing the cracked by-products, such as methane and ethylene, derived from propane cracking reaction on external Brønsted acidic sites of zeolite. Herein, chemical liquid deposition (CLD) method was adopted to passivate the external strong Brønsted acid of Ga/HZSM-5, aiming to increase the most value-added BTX production by suppressing the undesired propane cracking reaction. The content of deposited SiO 2 on the external surface of zeolite was tunable by varying the amount of liquid deposition reagent and duration time of CLD process. The results showed that an appropriate content of SiO 2 on external surface of catalyst was beneficial to disable the external strong Brønsted acid sites. Due to depressing the undesired propane cracking reaction, BTX selectivity of 55% with propane conversion of 49% was achieved on Ga/Z5-4Si catalyst, higher than those of Ga/HZSM-5. Otherwise, prolonging the duration time of CLD process narrowed the micropore mouth size of zeolite, which could enhance the shape selective effect of Ga/ZSM-5 to increase the proportion of para-xylene in total xylene products. [ABSTRACT FROM AUTHOR]

• Reflux improves the activity, stability and coke resistance of Ni/ZrO 2 catalyst. • Si and K are inevitably residual during the reflux process within basic solution. • Reflux can promote Ni dispersion, enrich the porosity and strengthen the basicity. • Residual Si and K ions stabilize metastable phase and affect acid-base properties. • Metastable structure is somewhat destroyed under long-life or high temperature run. Ni/ZrO 2 catalyst has been widely investigated for dry reforming of methane (DRM), but it suffers from rapid deactivation due to nickel aggregation and carbon deposition under the harsh conditions. Herein, we introduce the post-treatment of reflux in Ni/ZrO 2 catalyst prepared by the conventional co-precipitation method. The detailed characterization results demonstrate that the catalysts after reflux exhibit the metastable structure with enlarged specific surface area and abundant porosity, thereby highly dispersing the active Ni species. The residue of Si and K is inevitable during the reflux process under the basic solution and the residual amount increases with the extended reflux time and the raised solution pH value. The residual Si is undesirable to improve the acidity while the residual K is expected to enhance the desirable basicity. Therefore, the stabilized metastable structure and mediated properties should be considered comprehensively in practically designing the highly active and stable DRM catalyst. The evaluation at 700 °C with gas hourly space velocity of 50000 mL·g−1·h−1 (volume ratio: CH 4 /CO 2 = 1/1) and time on stream of 600 min demonstrates that the treatment of reflux remarkably improves the activity and stability of Ni/ZrO 2 catalyst. Especially, the catalyst with 5-day reflux displays the robust activity (CH 4 conversion: ~72%, CO 2 conversion: ~80%) and carbon-resistant ability (0.01 mg/mg cat.). However, although the metastable structure is somewhat stabilized by the treatment of reflux and the residual ions, eventually it is easily destroyed when suffering from long-life (6000 min) or high-temperature (beyond 800 °C) run, behaving as the sintering of Ni particles and carbon deposition. [ABSTRACT FROM AUTHOR]

Rare-earth element is efficient to enhance the surface adsorbed oxygen species. CH4 and CO2 reactivity are accelerated by the surface adsorbed oxygen species. Carbon deposition is mainly formed at the initial stage and subsequently inert. Rate gap between carbon deposition and removal is strongly affected by temperature. During dry reforming of methane, oxygen species over the catalyst surface play an important role in CH 4 /CO 2 reactivity, catalytic performance and carbon deposition. Herein, the effects of the surface adsorbed oxygen species tuned by doping with different rare-metal metals (such as Ce, La, Sm and Y) on the catalytic behavior were elaborated systematically. It was found that Y-doped catalyst exhibited the most amount of surface adsorbed oxygen species, followed by Sm, La, Ce and non-doped catalysts. The results confirmed that the surface adsorbed oxygen species were remarkably beneficial to enhance both CO 2 activation and CH 4 dissociation. Nevertheless, carbon formation and removal did not keep pace at low temperature due to more promotional effects of the surface adsorbed oxygen species on CH 4 dissociation than CO 2 activation. The gap between carbon deposition and removal was potential to be ameliorated through the accelerated activation to CO 2 at high temperature. [ABSTRACT FROM AUTHOR]

Controllable synthesis of hierarchical zeolites from natural aluminosilicate minerals is considered an efficient and eco-friendly approach for the production of high-performance zeolites, but its synthesis mechanism is still obscure. Herein, we take the synthesis of a single-crystalline hierarchical NaA zeolite using submolten salt depolymerized kaolin (SMS-K) as the sole source of silicon and aluminum via a mesoscale reorganization strategy as an example to elucidate the reorganization process. Comprehensive morphological and structural analyses reveal that sodium-rich voids in SMS-K facilitate concurrent assembly both within the interior and at the interface of the amorphous gel, leading to the formation of numerous nanoparticles with short-range order which assemble into single-crystal nanocube NaA zeolites with intracrystalline mesopores. By harnessing confinement effects, SMS-K modulates the growth of nanoparticle sizes and enhances the intimate interconnection of nanocubes, thereby yielding NaA zeolite aggregates that exhibit hierarchical porosity, encompassing micro-, meso-, and macropores. This study offers the potential for designing and precisely controlling the fabrication of hierarchical zeolites derived from natural minerals.

Selective oxidation of C-H bonds under mild conditions is one of the most important and challenging issues in utilization of energy-related molecules. Molybdenum oxide nanostructures containing Mo 5+ species are effective for these reactions, but the accurate identification of the structure of active Mo 5+ species and the catalytic mechanism remain unclear. Herein, unsaturated penta-coordinated Mo 5c 5+ with a high fraction in MoO x fabricated by the hydrothermal method were identified as the active sites for low-temperature oxidation of dimethyl ether (DME) by the deep correlation of characterizations, density functional theory calculations, and activity results, giving a methyl formate selectivity of 96.3% and DME conversion of 12.5% at unreported 110 °C. Low-temperature electron spin resonance (ESR) and quasi in situ X-ray photoelectron spectra (XPS) with the designed experiments confirm that the Mo 5c 5+ species can be formed in situ. Molybdenum located at the pentachronic site is preferable to significantly promote the oxidation of the C-H bond in CH 3 O* at lower temperatures., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

As important platform compounds, methanol and dimethyl ether (DME) are vital bridges between the coal chemical, petrochemical and fine chemical industries. At present, the synthesis of methanol/DME has been industrialized, and the production capacity is much larger than the market demand. Therefore, the conversion of methanol/DME into more valuable chemicals is an important and significant topic. The synthesis of high value-added oxygenated chemicals and diesel oil additives from methanol/DME by an oxidation method has attracted substantial attention due to it being green and environmentally friendly and having good atom economy. In this feature article, we have summarized the recent advances in the synthesis of formaldehyde, methyl formate, dimethoxymethane, and polyoxymethylene dimethyl ethers, from the selective oxidation of methanol/DME, and further discussed the adsorption and activation of reactant molecules, selective cleavage of C-O, C-H or O-H bonds in methanol/DME molecules and the C-O chain growth in the target products. In the end, major challenges and future prospects are proposed from the viewpoint of catalyst design and application. It is expected that this feature article will provide theoretical guidance for the activation and cleavage of C-O, C-H, or O-H bonds in other small molecules of alcohol/ether as well as low-carbon alkanes, so as to synthesize high value-added chemicals.

Inspired by natural photosynthesis, the design of new Z-scheme photocatalytic systems is very promising for boosting the photocatalytic performance of H 2 production and CO 2 reduction; however, until now, the direct synthesis of efficient Z-scheme photocatalysts remains a grand challenge. Herein, it is demonstrated that an interesting Z-scheme photocatalyst can be constructed by coupling In 2 O 3 and ZnIn 2 Se 4 semiconductors based on theoretical calculations. Experimentally, a class of ultrathin In 2 O 3 -ZnIn 2 Se 4 (denoted as In 2 O 3 -ZISe) spontaneous Z-scheme nanosheet photocatalysts for greatly enhancing photocatalytic H 2 production is made. Furthermore, Mo atoms are incorporated in the Z-scheme In 2 O 3 -ZISe nanosheet photocatalyst by forming the MoSe bond, confirmed by X-ray photoelectron spectroscopy, in which the formed MoSe 2 works as cocatalyst of the Z-scheme photocatalyst. As a consequence, such a unique structure of In 2 O 3 -ZISe-Mo makes it exhibit 21.7 and 232.6 times higher photocatalytic H 2 evolution activity than those of In 2 O 3 -ZnIn 2 Se 4 and In 2 O 3 nanosheets, respectively. Moreover, In 2 O 3 -ZISe-Mo is also very stable for photocatalytic H 2 production by showing almost no activity decay for 16 h test. Ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy, transient photocurrent spectra, and electrochemical impedance spectroscopy reveal that the enhanced photocatalytic performance of In 2 O 3 -ZISe-Mo is mainly attributed to its widened photoresponse range and effective carrier separation because of its special structure., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A series of SiO 2 -supported and γ-Al 2 O 3 -supported nickel phosphides were prepared by temperature-programmed reduction (TPR) with different calcination and reduction temperatures. The prepared catalysts were characterized by XRD, BET, H 2 -TPR, CO titration and HRTEM. The crystal phase and CO uptake content were influenced by calcination and reduction temperature. The catalytic performance of various catalysts was tested in quinoline hydrodenitrogenation and exhibited considerable differences. The quinoline HDN activity of SiO 2 -supported nickel phosphides decreases with increase of calcination and reduction temperature. In contrast to SiO 2 -supported samples, the ability to remove nitrogen of γ-Al 2 O 3 -supported samples increases with reduction temperature., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)