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The metal-organic framework Ni-MOF-74 was synthesized and then characterized by XRD, SEM, and N 2 adsorption techniques. The unary isotherms of CO 2 , CH 4 , C 3 H 6 , and C 3 H 8 on Ni-MOF-74 were measured by means of a volumetric method. The Langmuir–Freundlich model appropriately describes the adsorption equilibrium data. The selective separations of two mixtures CO 2 /CH 4 and C 3 H 6 /C 3 H 8 on Ni-MOF-74 were experimentally investigated by a breakthrough-column technique. Simulations of transient breakthroughs for the two mixtures agree well with the experimental data. In addition, with the inclusion of intra-crystalline diffusion into the simulations, the quality of the simulated breakthrough curves are improved and agree better with the experimental data. The results indicate that Ni-MOF-74 might be a candidate for the removal of C 3 H 6 from C 3 H 6 /C 3 H 8 mixtures and for the efficient separation of CO 2 from CH 4 . [ABSTRACT FROM AUTHOR]

• Microkinetic analysis is used to screen perovskites for methane partial oxidation. • The catalytic activity varies in the order LaMnO 3 > LaFeO 3 > LaCoO 3 ≈ LaCrO 3. • Bulk oxygen vacancy formation energy is identified as a single descriptor. • 667 combinations of A- and B-cations have been screened in terms of stability. • SrRuO 3 , SmRhO 3 , LaIrO 3 , NdRhO 3 , and BaOsO 3 are identified as catalyst candidates. DFT calculations and descriptor-based microkinetic analysis have been performed to screen ABO 3 perovskite catalysts for methane partial oxidation. The scaling relations indicate the adsorption energies of H@O and CH 3 @B have the capability of representing the energetics of methane oxidation, and bulk oxygen vacancy formation energy is identified to be a better single descriptor of the kinetics. The resultant volcano-shaped plot shows the catalytic activity varies in the order LaMnO 3 > LaFeO 3 > LaCoO 3 ≈ LaCrO 3 , which agrees with the experimental findings and thus validates our theoretical predications. By screening 667 combinations of A- and B-cations based on electron neutrality, structural tolerance factors, and experimental verification, 77 ABO 3 have been identified to be stable. Of them, SrRuO 3 , SmRhO 3 , LaIrO 3 , NdRhO 3 , and BaOsO 3 are located at the summit of the volcano, which also exhibit satisfactory CO selectivity and enhanced carbon resistance compared to LaFeO 3 , and may act as the oxygen carrier candidates. [ABSTRACT FROM AUTHOR]

• A assessment framework of methanol production integrated with a hybrid hydrogen strategy is established. • To comprehensively utilize hydrogen, "balance points" are proposed and defined. • The detailed techno-economic-environment performance are calculated. • The novel hybrid hydrogen supply strategy shows superior performance. A techno-economic-environment assessment framework of methanol production from coal integrated with a hybrid hydrogen supply strategy is established, gathering an insightful perspective of its broad sustainability and providing an effectually hybrid green, blue, and gray hydrogen supply plan to evaluate its performance. Process simulation and life-cycle analysis indicate that coal to methanol integrated with reverse water gas shift using coal to hydrogen (CTM-RWGS-CTH) and CTM-RWGS with water electrolysis using wind energy process show relatively independent excellent technical and environmental performance, respectively. To comprehensively utilize hydrogen energy to realize process integration and intensification, "balance points" are proposed and defined. Moreover, eleven possible hybrid hydrogen supply modes are developed and analyzed. Results show that the quaternary H 2 supply strategy exhibits enormous economic advantages, 0.051 $/kg methanol. The "balance point" in the quaternary H 2 supply strategy is CTM-RWGS-CTH 13%, CTM-RWGS H 2 from CTH without carbon capture, utilization and storage 37%, CTM-RWGS H 2 from byproduct gas to hydrogen 16%, and CTM-RWGS H 2 from water electrolysis using wind energy process 34%. Our hybrid hydrogen supply strategy embraces the full potential role of emerging CTM-RWGS processes to achieve low-carbon consumption and cleaner production, which should prevail over purely unitary hydrogen resources. [ABSTRACT FROM AUTHOR]

This study proposed a super thermal integrated process for CO 2 capture by using internal thermal integration to reduce the total energy efficiency loss of the power plant. [Display omitted] • Super thermal integrated adsorption carbon capture process (STILT) is proposed. • The detailed modeling steps for the novel STILT process are carried out. • The compared analysis of energy efficiency and capture costs are calculated. • The novel process shows superior techno-economic-environment performance. The heat-integrated solid adsorbent process exhibits the potential to become an energy-saving method for CO 2 capture. Here, a super thermal integrated process (STILT) for CO 2 capture is proposed based on our experimental data. The novel process strengthened the process of internal thermal integration and significantly improved the total energy efficiency. This study further takes the commercial MEA process as the benchmark for the multi-dimensional assessment (considering the techno-economic-environment). When CO 2 products are compressed to 110 bar, the energy efficiency of the STILT process and MEA process is 53.45 % and 48.8 %, and the energy consumption is 1.5 MJ/kgCO 2 and 3.41 MJ/kgCO 2. Without CO 2 compression, the energy efficiencies of the STILT process and MEA process are 55.3% and 50.61%. The energy consumptions are 0.82 MJ/kgCO 2 and 2.63 MJ/kgCO 2. Due to the combination of internal thermal integration and enhanced CO 2 circulation capacity, the capture costs of the STILT process are 25.8–34.94 €·t−1 CO 2 , which significantly outweigh the MEA process (43.3–55.07 €·t−1 CO 2). This exhibits the superior techno-economic-environment advantages of the STILT process. This study harbors tremendous referential significance for the design and scale-up of the industrial CO 2 capture process. [ABSTRACT FROM AUTHOR]

Sub-nanometer-sized Cu 6 and Au 6 clusters are stably anchored on the oxygen-deficient anatase TiO 2 surface, where Cu 6 -(V O)-TiO 2 shows high catalytic activity and satisfactory selectivity toward MG. [Display omitted] • The size and structure of stable Cu and Au clusters on TiO 2 are determined. • Oxygen vacancies can stabilize sub-nanometer-sized metal clusters. • Ti 5c and Cuδ+/Auδ- ions are coordinated to reaction intermediates. • The activity of Cu 6 -(V O)-TiO 2 (1 0 1) shows strong temperature sensitivity. • Cu-TiO 2 has good catalytic performance for DMO hydrogenation and MG production. The electronic structures of Cu-TiO 2 and Au-TiO 2 and their catalytic behaviors in the hydrogenation of dimethyl oxalate (DMO) have been studied by the stochastic surface walking-global neural network potential method, density functional theory calculation, and microkinetic analysis. Calculated results indicate that metal clusters on the pristine and oxygen-deficient TiO 2 are mostly coordinated to O 2c ions, and the defective surface may provide additional oxygen vacancies for Cu 6 and Au 6 cluster anchoring. It turns out that the interfacial Ti 5c and Cuδ+/Auδ- ions provide adsorption and hydrogenation sites for the reaction intermediates with unsaturated O and C atoms, respectively. The turnover frequency for DMO consumption is much higher on Cu-TiO 2 than on Au-TiO 2 , Cu(1 1 1), and Cu(2 1 1) at 443.15 K and 20 bar of total pressure. Given the satisfactory methyl glycolate (MG) selectivity, the Cu-TiO 2 catalyst has the potential to act as an excellent catalyst for the selective MG production. [ABSTRACT FROM AUTHOR]

Highlights • Water-assisted O 2 activation to form active OH∗ intermediates is in equilibrium. • The OH∗ species-assisted C H bond cleavage of glycerol is the possible RDS. • The oxidation of the primary and secondary hydroxyl groups have similar mechanism. Abstract Fundamental understanding of heterogeneously catalyzed aerobic, base-free oxidation of glycerol is highly desirable for sustainable and highly efficient chemical synthesis. In this work, Pt/CNTs catalyzed base-free oxidation of glycerol is investigated by combining experiments, DFT calculations and kinetics analysis. The solvent effects and kinetic isotope effects measurements as well as DFT calculations reveal that water-assisted O 2 activation to form active OH∗ intermediates is not in rate-determining step (RDS) but in equilibrium. Then, Langmuir-Hinshelwood kinetic models are developed and fitted with the experimental data. The OH∗-assisted C H bond cleavage of glycerol is discriminated as the RDS for the two parallel oxidation pathways of glycerol via primary or secondary hydroxyl groups, where the former case exhibits lower activation energy. The insights revealed here could guide the design and optimization of this catalytic process to generate the targeted products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Both size and support effects of Au catalysts are explored for MAL conversion. • The Au edge site is identified as the main active site for MMA generation. • A kinetics strategy for disentangling Au geometric and electronic effects is presented. The direct oxidative esterification of methacrolein (MAL) has drawn considerable attention as a promising route to produce methyl methacrylate (MMA). Here, we report a kinetics strategy to identify the active sites of Au catalyst for its disentanglement of geometric and electronic effects on this reaction. A series of Al 2 O 3 and CeO 2 supported Au catalysts are prepared by urea deposition–precipitation method, whose particle sizes are tailored by changing the vacuum-drying temperature. Their catalytic activity is correlated with Au particle size based on a crystal structure modelling, in which the Au edge site is identified as the main active site. The reduction in the valence electron population of Au 5 d states facilitates the adsorption of MAL, thus the positive core-level shift of Au 4f levels for each support gives rise to a higher production of MMA. This kinetics strategy could be extended to the design of other metal catalysts for this reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] For the explosive and strongly exothermic direct propene epoxidation with H 2 and O 2 to synthesize propylene oxide, maintaining uniform gas flow and moderate reaction in the packed bed reactor is of prime industrial and scientific significance. Herein, randomly packed beds of spherical particles were simulated with resolved particle 3D computational fluid dynamics (CFD) under industrial conditions. Effect of particle size (i.e., 6, 8 and 10 mm) on performance of gas-phase propene epoxidation was numerically simulated. The fluid flow and temperature fields were fully coupled to the species and reaction distribution, including reactions in the particles and on catalyst surface. Based on the results of velocity, pressure drop, temperature and species distribution, heat transfer together with catalytic performance inside the fixed bed reactor, it is found that PPD-6 (Packed Particle Diameter 6 mm) model has a more uniform flow distribution, higher thermal conductivity and a lower temperature compared with PPD-8 and PPD-10. In addition, as packed particle diameter increases, the heat transfer capacity reduces and the temperature rise increases. As a result, the maximum hot spot temperature for the PPD-6 model is about 3 and 8 K lower than PPD-8 and PPD-10 model, respectively. In addition, the PPD-6 model has a more uniform reaction rate within the particles compared with the PPD-8 and PPD-10 models due to short diffusion path and high mass transfer capacity. Therefore, the PPD-6 model shows superior safety together with optimum conversion and selectivity. This work harbors tremendous referential significance to the design and scale-up of industrial reactors for propene epoxidation. [ABSTRACT FROM AUTHOR]

The activated carbon treated at different temperatures was performed as a catalyst for the oxidation of glycerol to glycolic acid. Heat treatment at suitable temperature could promote the enrichment of ester and carboxyl functional groups with strong electronegativity, which serves as the efficient active site for the glycerol oxidation. Therefore, the optimal AC-400 catalyst with more ester and carboxyl groups shows excellent catalytic activity (0.0039 mol/g Cat /h) and GLYOA selectivity (53.2%). [Display omitted] • The efficient oxidation of glycerol to glycolic acid was realized over heat treated activated carbon. • Heat treatment tuned the composition and electronic structure of oxygen-containing functional groups. • The ester and carboxyl functional groups with strong electronegativity enhanced the adsorption and activation of glycerol. Exploring efficient and cheap catalyst for the selective oxidation of glycerol to valuable carboxylic acids is a critical and complicated challenge. Herein, we innovatively realized the efficient oxidation of glycerol to glycolic acid over metal-free catalyst under mild conditions via carbon material defect engineering. Multiple characterizations revealed that the stepwise functionalization of active carbon caused by simple high temperature control is adopted to fine-tune the composition and electronic structure of oxygen-containing functional groups. Specifically, the abundant ester and carboxyl functional groups exhibit stronger electronegativity than the hydroxyl group, and this enhanced electronic coupling effect strengthens the adsorption of glycerol, thus improving the catalytic activity. Kinetic analysis and density functional theory calculations demonstrated that the oxygen-containing functional groups (mainly ester and carboxyl) could promote the C–H bond activation of RCH 2 O* intermediate and once C–C bond cleavage of glyceric acid, ensuring the high selectivity of glycolic acid (53.2% over AC-400 catalyst). We anticipate that this work could sheds some light on the application and design of more new type of carbon-based metal-free catalysts in the aqueous phase oxidation of various polyols. [ABSTRACT FROM AUTHOR]

The finding that the MG selectivity increases and the DMO hydrogenation activity decreases with increasing the Ag nanoparticle size reveals the structure sensitivity of DMO partial hydrogenation. [Display omitted] • The structural sensitivity of DMO partial hydrogenation over Ag catalysts. • Ag stepped surfaces dominate the kinetics of the hydrogenation reaction. • The DMO consumption rate decreases with increasing the nanoparticle size. • The MG selectivity rises as the particle size changes from 5 nm to 10 nm. • A new strategy to ensure thermodynamic consistency of the reaction. Silver nanoparticles of different sizes have been synthesized to study their catalytic performance in dimethyl oxalate (DMO) partial hydrogenation to methyl glycolate (MG). Then, a detailed microkinetic analysis based on the results of DFT calculations has been performed to elucidate the origin of the observed size-dependent kinetics, where tabulated thermodynamic properties of gas-phase species are used to ensure the thermodynamic consistency of the reaction. Calculated results show that the turnover frequency for DMO consumption is much higher on Ag(2 1 1) than on Ag(1 1 1), suggesting the stepped surface dominates the kinetics. The hydrogenation of DMO on the two surfaces occurs along the same dominant reaction pathway, and the rate-determining step for the partial and deep hydrogenation of DMO is DMO and MG dissociation, respectively. The finding that the MG selectivity increases while the DMO hydrogenation activity decreases with the Ag nanoparticle size reveals the structure sensitivity of DMO partial hydrogenation. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanofibers (CNFs) were synthesized by CO disproportionation on iron catalyst at CO concentration between 58.3% and 75.0%, H2 concentration between 8.3% and 25.0% and reaction temperature between 833 and 913K. The time-depending rate of CNFs growth as a function of time was determined by an on-line mass spectrometer and the morphologies of all CNFs products were observed by electronic microscopy. Not only the CNFs growth rate but also the morphology of the grown CNFs were shown to vary with the three operating variables. SEM and TEM images showed that the three-dimensional morphologies of the CNFs were twist, helical or straight and an interesting relationship between the maximal growth rate and the morphology was observed. When the growth rate was between 0.8 and 0.9mmol/(sgcat), the CNFs were twist. As the growth rate increased to 1.0mmol/(sgcat), more helical nanofibers appeared. Straight nanofibers were produced when the growth rate reached the level of 1.2mmol/(sgcat). Finally when the rate of CNFs growth was high at 1.8mmol/(sgcat), the absolute majority of the solid products was amorphous carbon coexisting with some short and thick nanofibers. Under different operating conditions, the crystal faces of the catalysts had different anisotropy properties for carbon deposition, thus producing CNFs with different morphologies. [Copyright &y& Elsevier]

• Engineering of Ru atomic structure by fine-tuning Cl and Co coordination. • Acid-leaching of bimetallic catalyst for a 4.1-fold increase of H 2 generation rate. • Cl geometric effects of site blockage and steric hindrance as the main factors. • Kinetics switch from a Cl coverage-limited to a reactant activation regime. Herein, we demonstrate a strategy of engineering Ru atomic structures by fine-tuning Cl and Co coordination to synergize the quantity and quality of Ru active sites for boosting hydrogen generation from ammonia borane hydrolysis, via engineering the Cl-free/Cl-containing monometallic Ru catalysts and Co-leaching/Co-containing bimetallic Ru-Co catalysts. Under similar Ru particle sizes, the correlation between Ru binding energy and hydrogen generation activity affords a quantitative discrimination of Ru electronic and geometric contributions, where the site blockage and steric hindrance of Ru by Cl are more detrimental to hydrogen generation compared with the electronic modification by charge donation from Co to Ru. Reversely, the acid-leaching of Co from bimetallic catalysts creates abundant edge-like Ru active sites with much lower H 2 O activation barrier, as indicated by the kinetics switch from a Cl coverage-limited regime to a reactant activation regime, thus yielding a significant 4.1-fold increase in hydrogen generation activity. [ABSTRACT FROM AUTHOR]

We report the unique nanoscale alkaline earth metals doped Pt/M−MCM−41 (70) (M = Mg, Ca, Sr and Ba) catalysts for the selective oxidation of glycerol in base-free medium. Strong basic sites generated by alkaline earth metal oxides (especially MgO and CaO) could induce the strong electronic transfer ability, the modified reduction properties of Pt and abundant surface oxygen vacancies. Reaction kinetics demonstrated that the addition of alkaline earth metal oxide (e.g. CaO) could promote the activation of primary hydroxyl group and C-H bond, resulting in the excellent catalytic performance. • Basic strength-dependent catalytic performance for glycerol oxidation was investigated. • Alkaline earth metals changed the structural properties of the Pt/MCM-41 catalyst. • The promotion role of alkaline earth metal on the reaction mechanism was elucidated. • Record TOF values for the base-free oxidation of glucose and xylose were obtained. Fundamental understanding of basic site of supported metal catalysts is highly desirable for aqueous phase oxidation of alcohols without adding extra alkali. Herein, nanoscale alkaline earth metals doped Pt/M−MCM−41 catalysts (M = Mg, Ca, Sr and Ba) were prepared for the aqueous phase oxidation of glycerol to glyceric acid in base-free medium. By establishing the correlation between basic active site and catalytic performance, it is found that catalytic activity increases almost linearly with the strength of basic sites, and excessively strong basic sites are not conducive to the improvement of glyceric acid selectivity. Multi-characterizations revealed that strong basic sites generated by alkaline earth metal oxides (especially MgO and CaO) could induce the enhanced electronic transfer ability, the modified reduction properties of Pt and abundant surface oxygen vacancies in the Pt/M−MCM−41 catalysts. Moreover, reaction kinetics demonstrated that the addition of alkaline earth metal oxides (e.g. CaO) could promote the activation of primary hydroxyl group and C-H bond, resulting in the excellent catalytic performance. In addition, as the representative of the optimal solid base catalysts, the Pt/Ca-MCM-41 (70) catalyst also exhibits record high turnover frequency (TOF) values for the oxidation of glucose (9623.0 h−1) and xylose (4561.0 h−1) to corresponding carboxylic acids. [ABSTRACT FROM AUTHOR]