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A solvothermal route was developed to synthesize hierarchical TiO2 nanoflowers with tunable morphology, macroporous and mesoporous structure, and larger surface areas by varying the ratio of N,N-dimethylformamide to isopropyl alcohol without using surfactant and template. Morphology and microstructure, textural, crystalline, optical and photoelectric properties were characterized to investigate thoroughly the correlation of features and photoactivity of catalysts. The photoactivity was evaluated for the degradation of phenol through analyzing the phenolic compounds. The catalysts exhibited significantly high photocatalytic activity with the degradation rate of phenol of 95%, and the decrease of total organic carbon (TOC) was 82 ± 3% under ultraviolet radiation (UV) for 180 min at room temperature. Meanwhile, the excellent cyclic stability and regenerability were obtained during five cycles and continued illumination. The enhanced photocatalytic activity probably was attributed to larger surface areas, hierarchical porous structure, effective generation and separation of the charge carriers, and outstanding light-harvesting ability.

We propose a new strategy to make an active and stable Ni-based catalyst which can be operated in a wide range of reaction temperatures. The ordered mesoporous alumina (OMA) with confined Ni in the pore wall (Ni-OMA) was prepared via the one-pot evaporation induced self-assembly method. By using the incipient impregnation method, different amounts of free Ni were loaded over Ni-OMA (Ni/Ni-OMA) at a fixed total NiO content of 15 wt%. Characterization results confirmed the formation of well-structured Ni-OMA, and the ordered structure was still well preserved even after impregnating NiO at a content of as high as 12 wt%. The catalysts were evaluated for the CO methanation as a model reaction under varied conditions. Importantly, the activity and stability of Ni/Ni-OMA for the titled reaction were significantly regulated by simply changing the ratio of the confined to free Ni. Over the optimum catalyst of NiO (2 wt%)/NiO (13 wt%)-OMA, the high activity at a temperature of as low as 300 °C was achieved with the space-time yield of methane over 7.6 g gcat−1 h−1 while a long-term stability for a time-on-stream of 400 h was confirmed without an observable deactivation under the conditions of 600 °C and an extremely high gas hourly space velocity of 120,000 mL g−1 h−1. The results were well explained as the integrated merits of the free Ni for a high dispersion and the confined Ni in OMA for the anti-sintering property.

Catalytic conversion of CO2 into methanol is of particular interest as it does not only provide valuable methanol, but also utilize the waste CO2. In the present work, a CoO/Co/TiO2 catalyst was developed and utilized in catalyzing CO2 to methanol under photothermal conditions. From the results of characterization, the supported Co nanoparticles (NPs) were composed of Co0 in the bulk, CoO film formed from air oxidation on the surface, and Co0 at Co NPs-TiO2 interfaces. This structure provided the possibility for a Z scheme photothermal catalytic system, which revealed a high activity for methanol formation in aqueous media under atmosphere pressure. It was proposed that the light excited electrons from the valence band (VB) of TiO2, and the excited electrons could enhance the Co0 catalytic activity under thermal conditions. The present approach will offer a new strategy to design Co based Z scheme catalysts and further improve the conversion efficiency from CO2 to fuels.

In this work, we demonstrate that the amorphous silica-alumina composite (ASA) is an efficient solid acid for the steam reforming of dimethyl ether (SRD). Thus, a series of ASA with different Si/Al molar ratios was synthesized via the modified hydrolytic method by using Al(NO3)3·9H2O and/or NaAlO2 as Al precursor and tetraethoxysilane as Si precursor, respectively. Irrespective of the synthesis conditions, all of ASA composites were in an amorphous nature. However, both the acidity and the surface area were significantly affected by the synthesis conditions, the extent of which depends on the specific precursor and Si/Al molar ratios. The ASA physically mixed with a commercial Cu/ZnO/Al2O3 was investigated as a bifunctional catalyst for SRD under the conditions of P=0.1 MPa and gas hourly space velocity of 4000 h−1. Results indicate that both the conversion of dimethyl ether (DME) and the hydrogen yield were strongly dependent on the acidic property of ASA and the ASA to Cu/ZnO/Al2O3 ratios. Following the two-step consecutive mechanism of SRD, the catalytic results were well explained based on the acidic property of ASA, and the synergetic effect between the two catalytic functions was found to play a crucial role in determining the activity and stability of the bifunctional catalyst. Moreover, the DME hydrolysis was revealed to be the rate-limiting step for SRD reactions in the case of ASA as an acidic catalyst. By optimizing the synthesis conditions of ASA and the composition of the bifunctional catalyst, greater than 99% of DME conversion and hydrogen yield was achieved, and was kept for a time on stream of 66 h without an observable decrease. Thus, ASA is a very efficient solid acid for SRD.

The solid acid in metal-acid bifunctional catalysts for Fischer-Tropsch (FT) synthesis plays a crucial role for one-step selective synthesis of liquid fuels such as gasoline or diesel. In this work, the amorphous silica-alumina (ASA) synthesized by a one-step flame spray pyrolysis method (FSP) was demonstrated for the first time as an efficient solid acid for regulating the product distribution of FT synthesis. The 3 wt.% Ru impregnated ASA with different Al/(Al+Si) ratios was comparatively investigated for FT synthesis under typical conditions. The materials were characterized by XRD, STEM, H2-TPR, NH3-TPD, and N2 adsorption/desorption at low temperatures. In comparison with the ASA synthesized by the traditional sol-gel method, the ASA prepared by the FSP method showed clearly increased acidity. As a result, the selectivity of C13+ hydrocarbons was decreased while the selectivity of C5-12 hydrocarbons was increased, the extent of which is clearly dependent on the Al/(Al+Si) ratio of ASA. Moreover, both the carbon-chain length and the composition of olefins, normal and branched alkanes of FT products were easily regulated in a certain extent by simply changing the Al/(Al+Si) ratio of ASA. Thus, the enhanced and easily regulated acidity, rich porous structure, and available large-scale production of the ASA originated from FSP method make it an important solid acid for selective synthesis of liquid fuels via FT route.

Supported vanadium oxides are widely used as active catalysts for a number of oxidation and oxidative dehydrogenation reactions, and the understanding the structure-function relationship is of great importance for developing more efficient vanadium oxide catalysts. In this work, atomic layer deposition (ALD) was utilized to disperse sub-monolayer VOx over a commercial γ-Al2O3 support. Characterization results indicate that highly dispersed VOx species with different structures were obtained by simply changing the number of ALD cycles. The vanadium oxides synthesized by performing 1 cycle of ALD were exclusively isolated monomeric VOx. With increasing the number of ALD cycles from 3 to 8, the polymeric VOx spices were formed, and the polymerization extent or domain size of VOx was increased. On the contrary, crystalline V2O5 besides polymeric VOx was found if the number of ALD cycles was extended to 12. Catalytic performances of ALD VOx/γ-Al2O3 were evaluated for the oxidative dehydrogenation of ethylbenzene with CO2 (CO2-ODEB), and the isolated monomeric VOx species were found to be more active and more stable than the polymeric VOx species and crystalline V2O5. By correlating the specific activity and the structural characteristics of ALD VOx/γ-Al2O3 catalysts, the V O Al bonds were concluded as the key active sites for CO2-ODEB.

The zirconium doped ceria (Ce1-xZrxO2, x = 0.0, 0.1, 0.3, 0.5, 0.9, and 1.0) was synthesized via the urea-hydrolysis assisted hydrothermal method by using (NH4)2Ce(NO3)6 and ZrO(NO3)2·2H2O as the precursors. The structural and textural properties of the oxides were characterized with pertinent techniques, and the materials were evaluated as catalysts for the oxidative dehydrogenation of ethylbenzene with carbon dioxide (CO2-ODEB) under the conditions of 550 °C, 0.1 MPa, CO2 to ethylbenzene molar ratio of 20, and W/F = 8.07 g-cat·h∙mol−1. Characterization results indicate that the single-phase cubic solid solution was formed in the cases of Ce0.9Zr0.1O2, Ce0.7Zr0.3O2, and Ce0.5Zr0.5O2. In contrast, separated tetragonal and monoclinic phases of ZrO2 were present over Ce0.1Zr0.9O2 besides the solid solution. Moreover, the relative content of defects over the surface of Ce1-xZrxO2 was continuously increased with x, but the highest amount of reducible Ce4+ was obtained over Ce0.5Zr0.5O2. Reaction results indicate that Ce1-xZrxO2 was effective for CO2-ODEB, and the highest conversion of ethylbenzene was obtained over Ce0.5Zr0.5O2. The activity of Ce1-xZrxO2 for the titled reaction is determined by both the amount of the reducible Ce4+ and the easy oxidation of Ce3+ by CO2 over the catalyst. The inhibition of the coke via the oxidation of Ce3+ by CO2 and its promotional effect on the activity are responsible for the stability of the catalyst for CO2-ODEB.

The hollow-structured porous aromatic polymers (H-PAP) with cavity diameter from 228 ± 11 to 464 ± 15 nm were controllably prepared through surface coating and template-etching method under scalable synthesis conditions from standard scale to 20-fold scale-up. It is found that the fill factor (f) of reactor is an important parameter for determining the scalability of synthesis. Benefiting from the favorable textural properties, chemical and thermal stability, surface hydrophobicity and π electrons, the well-developed H-PAP as adsorbent was investigated in selective adsorption of 5-hydroxymethylfurfural (HMF) under static batch mode from the single-component and multi-component aqueous solutions. The H-PAP shows an exclusive adsorption for HMF, without adsorption of fructose, levulinic acid (LA) and formic acid (FA), and can be recycled three times without significant decrease in adsorption capacity. Structure-performance relationship points out that the apparent amount of HMF adsorbed on H-PAP is related to micropore surface area, micropore volume and cavity diameter, while HMF selectivity depends on surface hydrophobicity. In the case of HMF adsorption from the real reaction mixture of acid-catalyzed fructose dehydration, the HMF constituent with high purity (ca.94.4%) can be recovered. Combining the adsorption isotherms with DFT calculation reveals adsorption mechanism that HMF adsorption on H-PAP proceeds initially via π–π stacking interaction, and then assembles into regular array around spherical surface to form monolayer coverage following modified Langmuir model, and finally diffuses into interior cavity until adsorption saturation.

The size effect of the metallic Co (Co0) over supported catalysts for Fischer-Tropsch synthesis (FTS) has imposed great importance for developing a high-performance catalyst. However, the lack of well-structured catalysts makes the clarification of the intrinsic size-dependence of Co0 still a challenge. In this work, the Co/C catalysts with Co0 particles from 8.4 ± 1.9 to 74.8 ± 11.6 nm were synthesized by well-controlled pyrolysis of ZIF-67. Based on different characterizations, Co/C catalysts via pyrolyzing ZIF-67 above 450 °C were confirmed as Co0 entrapped in partially graphitized carbon matrix polished by a certain amount of pyridinic and graphitic N and a small portion of adsorbed oxygen. Without the limitation of high-temperature reduction and the dispersion-reducibility dependence, the intrinsic size effect of Co0 on the activity and product selectivity of FTS was rigorously revealed, and the critical size was determined to be 10.5 ± 1.9 nm.

Improving the intrinsic catalytic activity of NiFe layered double hydroxide (LDH), which is a benchmark electrocatalyst for oxygen evolution reaction (OER), is a significant challenge. In the present study, we doped ruthenium ions into NiFe LDH (Ru-NiFe LDH) to accelerate the OER kinetics. Electrochemical measurements of NiFe LDH and Ru-NiFe LDH at similar mass loadings showed that Ru-NiFe LDH demonstrated a higher OER activity than that of NiFe LDH. Ru-NiFe LDH only requires an overpotential of 246 mV at 10 mA cm−2 in alkaline media. This attributes to ruthenium doping primarily, which can promote the catalytic activity of Fe sites and boost the electronic interaction among the Ni, Fe, and Ru metals according to the theoretical calculations. Ru-NiFe LDH is stable during OER stability measurements, which was confirmed by structure and elemental analysis. These findings will provide a useful approach for promoting the intrinsic activity of multi-metallic (oxy) hydroxide electrocatalysts toward the OER.

Developing highly efficient, stable, and earth-abundant heterogeneous electrocatalysts for the oxygen evolution reaction (OER) is a significant challenge. Herein, we designed and synthesized a novel core–shell trimetallic Ni0.70Fe0.10V0.20S2 @ amorphous NiFe hydroxide for enhancing OER kinetics using thermal sulfidation and in situ electrochemical tuning methods. Electrochemical testing of various as-prepared catalysts at the same mass loading demonstrated that the trimetallic Ni0.70Fe0.10V0.20S2 @ amorphous NiFe hydroxide possessed the highest intrinsic activity for the OER compared to other reference catalysts. Furthermore, the heterostructures are directly grown on a carbon paper with a high surface area and good conductivity to form an integrated 3D electrode with an overpotential of 204 mV at the current density of 10 mA cm-2 and a small Tafel slope of 39 mV dec-1 in 1.0 M KOH electrolyte. This is one of the most effective OER electrocatalysts. X-ray photoelectron spectroscopy and scanning electron microscopy indicated that the material structure and chemical composition of Ni0.70Fe0.10V0.20S2 @ amorphous NiFe hydroxide exhibited good stability under harsh OER conditions. These advantages could be mainly attributed to the synergistic effect between the core and shell, high electronic conductivity of the core, and more active sites on the surface of the amorphous shell. Additionally, this study provides novel insights for designing and synthesizing heterostructure multimetallic disulfides electrocatalysts for OER in the future.

The selective hydrogenation of CO2 to value-added chemicals is attractive but still challenged by the high-performance catalyst. In this work, we report that gallium nitride (GaN) catalyzes the direct hydrogenation of CO2 to dimethyl ether (DME) with a CO-free selectivity of about 80%. The activity of GaN for the hydrogenation of CO2 is much higher than that for the hydrogenation of CO although the product distribution is very similar. The steady-state and transient experimental results, spectroscopic studies, and density functional theory calculations rigorously reveal that DME is produced as the primary product via the methyl and formate intermediates, which are formed over different planes of GaN with similar activation energies. This essentially differs from the traditional DME synthesis via the methanol intermediate over a hybrid catalyst. The present work offers a different catalyst capable of the direct hydrogenation of CO2 to DME and thus enriches the chemistry for CO2 transformations., The conversion of CO2 to valuable chemicals is still challenged by catalyst developments. Herein, the authors found that GaN is an efficient catalyst for selective CO2 hydrogenation to dimethyl ether as the primary product, in contrast to the traditional methanol-intermediate route over hybrid catalysts.

The minimized diffusion limitation and completely exposed strong acid sites of the ultrathin zeolites make it an industrially important catalyst especially for converting bulky molecules. However, the structure-controlled and large-scale synthesis of the material is still a challenge. In this work, the direct synthesis of the single-layer MWW zeolite was demonstrated by using hexamethyleneimine and amphiphilic organosilane as structure-directing agents. Characterization results confirmed the formation of the single-layer MWW zeolite with high crystallinity and excellent thermal/hydrothermal stability. The formation mechanism was rigorously revealed as the balanced rates between the nucleation/growth of the MWW nanocrystals and the incorporation of the organosilane into the MWW unit cell, which is further supported by the formation of MWW nanosheets with tunable thickness via simply changing synthesis conditions. The commercially available reagents, well-controlled structure and the high catalytic stability for the alkylation of benzene with 1-dodecene make it an industrially important catalyst., The single- to fewer-layer ultrathin MWW zeolite with controlled structure, high crystallinity and excellent thermal/hydrothermal stability was facilely synthesized by using commercially available structure-directing reagents, which makes it an industrially important catalyst for converting bulky molecules.

Bimetallic Ni@Ru nanoparticles with Ni core and Ru shell supported on SiO2 were prepared by impregnation method using a perovskite-type oxide of LaRuxNi1−xO3 as the precursor and used as catalysts for CO methanation. The catalysts were characterized by using BET, XRD, H2-TPR, HRTEM + EDX, ICP, H2 chemisorption, XPS and TGA techniques. By reducing the catalysts with hydrogen, bimetallic nanoparticles with the structure of nickel shell and ruthenium core of Ru@Ni supported on SiO2 doped with La2O3 were made, and the Ru would migrate to the surface of the Ni-Ru cluster forming the ruthenium shell and nickel core of Ni@Ru under CO atmosphere. The supported bimetal catalysts with core–shell structure by doping small amount of noble metal exhibited very good catalytic performance for CO methanation, especially showed excellent resistance to carbon deposition and metal sintering, while the monometallic catalyst of nickel showed inferior catalytic performance.

Three treatment parameters of supercritical CO2 have been optimized by a response surface method using central composite design to obtain isolate yield of flax rove. Influence of operating parameters including dosage of cellulase, temperature, and pressure on final response is evaluated. The results show that the experimental values are adequately fitted to a quadratic polynomial equation. The optimal isolate yield is obtained with 2% cellulase dosage under temperature of 50?C and pressure of 20 MPa. Mathematical model is also applied to describe the kinetic behavior of the treatment process, revealing that supercritical CO2 is a promising green solvent for the scouring and bleaching of flax rove.

The electrocatalytic oxygen evolution reaction (OER) requires stable, highly active, and robust earth-abundant electrocatalysts. In the present study, we combine theoretical simulations with experimental approaches to design and synthesize NiFeW layered double hydroxide (LDH) for efficient OER in alkaline electrolytes. Density functional theory with the Hubbard U (DFT + U) calculations suggests that W, a high-valence metal, can improve the catalytic activity of Fe sites and optimize adsorption energies for OER intermediates at the surface of NiFeW LDH. Electrochemical measurements of the as-synthesized NiFeW LDH with a constant mass loading reveals that the LDH with the NiFeW molar ratio of 4:1:1 presented the highest intrinsic OER activity among all bi- and trimetallic LDH catalysts in this study. Furthermore, the nanostructures with the optimal active metal molar ratio are in situ grown on hydrophilic-treated carbon paper to fabricate an integrated 3D electrode with an overpotential of 248 mV at the catalytic current density of 20 mA cm−2 and a low Tafel slope of 68 mV dec−1 in 1.0 M KOH solution. This indicates that NiFeW LDH is among the most active NiFe-based OER electrocatalysts reported to date. X-ray photoelectron spectroscopy and elemental analysis confirm that the optimized Ni Fe W LDH presents a stable chemical composition and Ni, Fe, and W are still present in the catalyst after alkaline OER measurements. These findings offer new insights and avenues for the future design and study of stable and active multi-metal-based OER electrocatalysts.

Although the supported chromium oxides are important industrial catalysts for a number of reactions including the propane dehydrogenation, the rational catalyst design is still challenged by the deficient understanding on the active and selective nature of the catalysts. In this work, CrOx/silicalite-1 with a Cr loading of 0.5–5 wt.% prepared by the impregnation method is probed for the oxidative dehydrogenation of propane with carbon dioxide (CO2-ODP) under industrially relevant conditions. Characterization results reveal that CrOx is highly dispersed over silicalite-1, and crystal Cr2O3 is still very limited even over the catalyst with the highest Cr loading. Moreover, the isolated and polymeric Cr6+ oxides coexist over all of CrOx/silicalite-1 catalysts, and the amount and the extent of the polymerization of the Cr6+ oxides are continuously increased with increasing the Cr loading. Reaction results indicate that the CrOx/silicalite-1 is superior for CO2-ODP, and the highest space-time yield of 16.7 kg(C3H6) h−1 kgCr)−1 is obtained over the catalyst with a Cr loading of 2 wt.%. By correlating with the reaction results, the polymeric Cr6+ oxides with a high degree of the polymerization are determined to be the most active but least selective sites for CO2-ODP, which is originated from the varied adsorption strengths of C3H8 and the different desorption behaviors of C3H6 on the specifically structured Cr6+ oxides over CrOx/silicalite-1. As a result of the strong adsorption of the C3H8 reactant and the produced C3H6 over the most active polymeric Cr6+ oxides, the deposited coke is found to play dual roles for both decreasing the C3H8 conversion and increasing the C3H6 selectivity. The catalytic results of CrOx/silicalite-1 for CO2-ODP are well explained with these understandings, which are important for guiding the development of the high-performance CrOx-based catalysts for dehydrogenation reactions, especially CO2-ODP.

The severe requirement of a higher activity at lower temperatures and a longer stability at higher temperatures evokes a great challenge for the development of an industrially viable catalyst for the CO methanation reaction. In this work, the Co-Ni bimetallic catalysts were synthesized via post-impregnating the cobalt precursor within the mesoporous channel of Ni-embedded ordered mesoporous alumina (Ni-OMA). The low-temperature activity and high-temperature stability of Co/Ni-OMA for the CO methanation were significantly regulated by easily tuning the ratio of free Co and confined Ni species. The optimal catalyst of 8Co/15Ni-OMA showed a high activity with the CH4 formation rate of 126 mol kgcat−1 h−1 at a temperature of as low as 300 °C and a long-term durability for a time-on-stream of 200 h without an observable deactivation under the conditions of 600 °C and an extremely high GHSV of 180000 mL g−1 h−1. Kinetics results reveal that the apparent activation energy of the CO methanation over 8Co/15Ni-OMA (100.2 kJ mol−1) was clearly lower than that over 15Ni-OMA (124.0 kJ mol−1) or 15Co-OMA (131.8 kJ mol−1). In the absence of mass transport and heat transfer limitations, three microkinetics models were developed following the H-assisted CO dissociation and Langmuir-Hinshelwood mechanism, which the H-assisted CO dissociation, the hydrogenation of surface carbon species (C*) or surface CH3* species are proposed as the rate-determining step, respectively. The kinetics behaviors over 15Ni-OMA and 8Co/15Ni-OMA are matched well with all of the kinetics models, indicating the same elementary sequence and rate-determining step. In the case of 15Co/OMA, the CH4 formation rate was predicted very well by the kinetics models derived from the stepwise hydrogenation of surface carbon species as the rate-determining step, and the kinetics model based on the H-assisted CO dissociation as the rate-determining step could be ruled out, indicating that the rate for the H-assisted CO dissociation rate is faster than that of the following stepwise hydrogenation. Based on the discrimination of different kinetics models, Ni species confined within OMA matrix were proposed as the dominant active sites for catalyzing the CO methanation, while the post-impregnated Co was acted as a promoter for the H-assisted CO dissociation. As a result, an enhanced low-temperature activity was achieved over the optimal 8Co/15Ni-OMA catalyst.

N-Graphitic-Modified cobalt nanoparticles supported on carbon powder (Co/phen@CB-800-L) were prepared and found to be efficient catalysts for selective oxidation of arylalkanes to aromatic ketones with tert-butyl hydroperoxide (TBHP) in water. A broad scope of substrates have been investigated, the desired products were obtained with yields as high as 99% under the optimized condition in all cases. Remarkably, this carbon powder supported catalyst could be recovered easily, and showed high activity within six successive runs.

An improved ammonia-based desulfurization technology was proposed, in which the produced excess NH4HSO3 was concentrated by using the heat from the Claus tail gas and then SO2 was recovered by decomposing the concentrated NH4HSO3 in the Claus furnace. Furthermore, the process was modeled and simulated using the commercial software Aspen Plus. The characteristics of the ammonia-based desulfurization model were validated and compared with experimental results. Moreover, the water balance in the system was maintained, therefore, no extra water was required. Under the water balance condition, the SO2 removal performance in the system was predicted with various operating conditions. The model exhibited a reliable prediction of the desulfurization performance of the innovative process, which will be favorable for actual industrial application.

A number of metallocalix[n]arenes, where n = 4, 6, or 8, of titanium and vanadium have been screened for their ability to act as catalysts for the co‐polymerization of propylene oxide and CO2 to form cyclic/polycarbonates. The vanadium‐containing catalysts, namely [VO(L1Me)] (1), [(VO2)L2H6] (2), [Na(NCMe)6]2[(Na[VO]4L2)(Na(NCMe))3]2 (3), [VO(μ‐OH)L3/H2]2∙6CH2Cl2 (4), {[VO]2(μ‐O)L4[Na(NCMe)2]2} (5), {[V(Np‐tolyl)]2L4} (6) and [V(Np‐RC6H4)Cl3] (R = Cl (7), OMe (8), CF3 (9)), where L1H3 = methylether‐p‐tert‐butylcalix[4]areneH3, L2H8 = p‐tert‐butylcalix[8]areneH8, L3H4 = p‐tert‐butylthiacalix[4]areneH4, L4H6 = p‐tert‐butyltetrahomodioxacalix[6]areneH6, performed poorly, affording, in the majority of cases, TONs less than 1 at 90°C over 6 h and low molecular weight oligomeric products (Mn ≤ 1665). In the case of the titanocalix[8]arenes, {(TiX)2[TiX(NCMe)]2(μ3‐O)2(L2)} (X = Cl (10), Br (11), I (12)), which all adopt a similar, ladder‐type structure, the activity under the same conditions is somewhat higher (TONs >6) and follows the trend Cl > Br > I; by comparison the non‐calixarene species [TiCl4(THF)2] was virtually inactive. In the case of 10, it was observed that the use of PPNCl (bis[triphenylphosphine]iminium chloride) as co‐catalyst significantly improved both the polymer yield and molecular weight (Mn 3515). The molecular structures of the complexes [HNEt3]2[VO(μ‐O)L3H2]2∙3CH2Cl2 (4∙3CH2Cl2), [VO(μ‐OH)L3/H2]2∙6CH2Cl2 (4/) (where L3/H2 is a partially oxidized form of L3H4) and {(TiCl)2[TiCl(NCMe)]2(μ3‐O)2(L2)}·6.5MeCN (10·6.5MeCN) are reported.

To investigate the effect of structural evolution of layered zeolite on the performance of Co/MCM-22 derived zeolites for Fischer–Tropsch (FT) synthesis, the MCM-22, MCM-36 and delaminated zeolite characterized by different arrangement of MWW nanosheets were prepared through directly calcination, pillaring and delaminating of the layered precursor of the MCM-22 (MCM-22(P)). The results show that the extent of reduction of cobalt was increased over Co-supported pillared and delaminated zeolites, and the activities of the catalysts (i.e., CO conversions) were increased in the order of Co/MCM-22

A betaine-type styrene monomer with the quaternary ammonium-borate anion inner-salt pair was synthesized through the quaternization reaction and polymerized to afford the target polybetaine of poly(4-vinylbenzyl methyl-diethanol ammonium borate) (PVMAB). The chemical structures of the monomer and polymer were well demonstrated with 1H-NMR and 11B-NMR spectra analysis. The thermal-sensitive experiment showed that PVMAB in water afforded gradually welldefined sigmoidal transmittance-temperature (T-t) curves along with the increasing polymer concentration. However, the phase transition temperatures at the bottom of the S-shaped curves were always below 10 °C due to the very weak zwitterionic association of the ammonium-borate inner-salt pairs. The UCST phase transition could also be tuned by changing the ethanol content in the ethanol/water mixture. And the cytotoxicity experiment demonstrated the good biomimetic property of PVMAB. This study enriches the toolbox of polybetaines by introducing the quaternary ammonium-borate anion zwitterionic pair in the repeat units, therefore broadens the scope of synthetic polybetaines.

The strong desire for developing promising candidates of insensitive nitro energetic materials has spurred numerous attempts to discern the nitration details. The nitration mechanism of 2-methyl-4,6-dihydroxypyrimidine (MDP) with nitronium (NO2+) to form 2-dinitromethylene-5,5-dinitropyrimidine-4,6-dione is studied via DFT-B3LYP/6-311G(d,p) method. The possible nitration pathways are excavated and illustrated. Herein, a unique/incredible induction/enhancement of the co-existing acidic group of HSO4− to the targeted nitration is definitively proposed. The impact of the introduction order of four nitro groups (–NO2) on the title nitration is systematically demonstrated. It is suggested that the proposed induction of HSO4− may effectively promote/catalyze not only the NO2+ attack, but the H-transfer and H-abstraction as well, and thus dramatically decreases the activation free energy of the nitration system. Moreover, the NO2+ attack may be dynamically affected by the pre-introduced –NO2 and the resulted fluctuation of charge distribution in the pre-intermediates, which has been primarily supported via the calculated atomic charge, Coulomb attraction and Fukui function. It is indicated that the preferential dinitration on –CH3 with the induction of HSO4− (path A) is the most likely pathway. It is optimistically expected that the present study may provide a theoretical basis to the research and engineering tests of the title nitration, and promote the exploration of related insensitive energetic materials.

Cost-effective adsorbents for volatile organic compounds elimination were synthesized at room temperature. New kinds of external cross-linkers were developed and used in the one-step Friedel–Crafts reaction. The synthesized polymers exhibit a high surface area (BET surface area up to 1345 m2 g−1), large pore volume, superhydrophobic nature and excellent adsorption capacity for benzene, which is one of the highest to date among the reported adsorbents. It also possesses super preferential selectivity towards benzene in a high humid gas stream. Therefore, this kind of material is a promising adsorbent for air purification and environmental protection.

A new kind of hydrophobic hyper-cross-linked polymers (HCPs) with high surface area, large pore volume, and controllable average pore size was prepared. The synthesized HCP-0.5 sample, having the biggest BET specific surface area (1394 m(2)/g), pore volume (1.55 m(3)/g) and micro-mesopore structure (average pore diameter of 4.4 nm), was used as a novel adsorbent for removing benzene. The results of the static adsorption/desorption experiment at 298,308 and 318 K showed that HCP-0.5 has a very large adsorption capability of 19.16 mmol g(-1) at 298 K for benzene. Dynamic adsorption experiments of benzene on HCP-0.5 under dry and humid condition (RH = 80%) revealed that the existence of water vapor had little effect on dynamic adsorption capacity of benzene on HCP-0.5 and almost did not change the breakthrough time. Therefore, these synthesized polymers can be used as efficient and competitive adsorbents for removing VOCs, especially under humid conditions. (C) 2015 Elsevier B.V. All rights reserved.

High pressure in situ Fourier transfer infrared/near infrared technology (HP FTIR/NIR) along with theoretical calculation of density functional theory (DFT) method was employed. The solvation behaviors and the free radical homopolymerization of methyl methacrylate (MMA), methacrylate acid (MAA), trifluoromethyl methacrylate (MTFMA) and trifluoromethyl methacrylate acid (TFMAA) in scCO2 were systematically investigated. Interestingly, the previously proposed mechanism of intermolecular-interaction dynamically-induced solvation effect (IDISE) of monomer in scCO2 is expected to be well verified/corroborated in view that the predicted solubility order of the monomers in scCO2 via DFT calculation is ideally consistent with that observed via HP FTIR/NIR. It is shown that MMA and MAA can be easily polymerized, while the free radical polymerizability of MTFMA is considerably poor and TFMAA cannot be polymerized via the free radical initiators. The &alpha, trifluoromethyl group (&ndash, CF3) may effectively enhance the intermolecular hydrogen bonding and restrain the diffusion of the monomer in scCO2. More importantly, the strong electron-withdrawing inductive effect of &ndash, CF3 to C=C may distinctly decrease the atomic charge of the carbon atom in the methylene (=CH2). These two factors are believed to be predominantly responsible for the significant decline of the free radical polymerizability of MTFMA and the other alkyl 2-trifluoromethacrylates in scCO2.

The hydrolysis mechanism and the kinetics of using 2-dinitromethylene-5,5-dinitropyrimidine-4,6-dione (NMP) to prepare the representative insensitive energetic material 1,1-diamino-2,2-dinitroethylene (FOX-7) in a nitric–sulfuric acid system are systematically investigated via a density functional theory (DFT) method. The impact of the co-existing acidic group of HSO4− as well as the solvent effects of the mixed acids on the hydrolysis of NMP are elucidated and discerned, and the proposed catalysis and promotion of the hydrolysis of NMP with HSO4− are verified. The HSO4−-catalyzed hydrolysis pathway is more favorable than the direct pathway as well as the H2O-catalyzed hydrolysis, indicating that HSO4− may be a promising catalyst for the preparation of FOX-7 in a mixed acid system. The present study is expected to provide a better understanding of the hydrolysis of NMP, and will significantly help with better preparation of FOX-7 and other nitro-energetic materials.

Nano-platinum granules were affixed to MWCNTs via a liquid-reduction method. Different methods were utilized to introduce Fe(III) into the Pt/MWCNT catalyst. The influence of Fe(III) on the performance of a selective citral hydrogenation over the Pt/MWCNTs in isopropanol was investigated. Characterization techniques such as XRD, TEM, TPR, XPS and N 2 physisorptions were used. Changes in the absorbance and wavenumber for the C O bond in the citral were monitored with a high-pressure in situ infrared spectrometer. When 0.25 wt.% Fe(III) was added, the citral conversion remained unchanged, but the selectivity toward the unsaturated alcohols increased from 33.7 to 90.7%.

The nitration mechanism as well as the kinetics of triazol-3-one (TO) with nitronium (NO2+) in both a concentrated nitric acid and a nitric–sulfuric acid system was theoretically studied. Firstly, the density functional theory (DFT) with a B3LYP functional was employed to investigate the mechanism of the mentioned reactants towards the targeted product, 5-nitro-2,4-dihydro-1,2,4-triazol-3-one (NTO). An unexpected induction effect, which derived from the coexisting acid group (NO3− and/or HSO4−), was proclaimed. The impact of the induction effect on the nitration of TO was systematically demonstrated. It is found that unlike the nitration of most aromatics, the nitration of TO with NO2+ to form NTO does not follow the typical electrophilic substitution mechanism. Based on the results calculated in each acid system, the nitration mechanisms, including the NO2+ direct nitration (path A), NO3−-induced nitration (paths Bn–Dn) and HSO4−-induced nitration (paths Bs–Ds), were proposed. It is indicated that path A is unlikely or unfavorable due to the high activation barrier in the rate-determining step, whereas paths Bn–Dn and Bs–Ds are favorable, mainly attributed to the significant decrease of the activation energy induced by NO3− and HSO4− during the nitration process, especially for the NTO-oriented path Bn and Bs. Secondly, the canonical variational transition (CVT) state theory with small curvature tunneling (SCT) correction was used and the rate constants of the rate-determining steps for all paths at different temperatures were calculated. It is shown that the nitration rate in either path Bn or path Bs outdistances that in path A, indicating that NO3− and HSO4− accelerate the nitration of TO with NO2+, and ultimately favour the formation of NTO due to the proposed induction effect of each acid group. An enhanced catalytic effect of the nitric acid or/and sulfuric acid is thought to be embodied in not only the acceleration to the formation of NO2+, but also the induction effects of NO3− and HSO4− during the nitration processes. Meanwhile, it is suggested that the concentration of nitric acid and sulfuric acid in each nitration system should be well controlled since the favourable condition to produce NO2+ and NO3−/HSO4− differs in the concentrations of the corresponding acids.

The mixed oxide of NiO, MgO, and Al 2 O 3 (NMA) with a MgO/Al 2 O 3 molar ratio of 3 was prepared from the hydrotalcite-like precursor, and ceria was introduced into NMA with Ce/Al molar ratios between 0.1 and 1.0 via the co-precipitation (NMACe) and the incipient impregnation (Ce/NMA) method, respectively. The NMACe and Ce/NMA were comparatively investigated to reveal the impact of ceria on NMA for carbon dioxide reforming of methane (CDR) under severe conditions. All of the catalysts were highly active for the pressurized CDR. On the contrary, a significant impact of the content and introduction method of CeO 2 on the catalytic stability was observed. Thus, the calcined, reduced, and/or used catalysts were systematically characterized by spectroscopic and adsorption techniques. Results indicate that the H 2 -TPR pattern of NMA was significantly influenced by the addition of CeO 2 , the extent of which is dependent on its content and introduction method. As a result, the degree of reduction and dispersion of Ni were clearly varied for different catalysts. Although the (1 1 1) planes of cubic CeO 2 were preferentially exposed over all of the catalysts, the content of Ce 3+ over Ce/NMA was apparently higher than that over NMACe, and the appropriate interactions between Ni and NMA were achieved over Ce/NMA with a Ce/Al ratio of 0.5. Because of the inhibited coke deposition, the alleviated graphitization of the deposited coke, and the delayed sintering of Ni, Ce/NMA with a Ce/Al ratio of 0.5 showed highly active and stable performance for the titled reaction under highly demanding operation conditions.

A novel, high-efficiency and high-selectivity construction of β-trifluoromethyl enol ether via base-induced/promoted C–O coupling of trifluoromethylated vinyl chloride and phenols is presented with a broad substrate scope. The reaction mechanism, especially the significantly high selectivity, was excavated and understood via DFT calculation and is well supported by the experimental observation.

Montmorillonite (MMT) modified with chitosan (CTS, molecular weight=5×10(4)) was applied to remove heavy metal cations by using Co(2+) as a model ion. An increase in MMT interlayer distance observed from X-ray diffraction indicates the intercalation of CTS into MMT. Together with the results of scanning electron microscopy and Fourier transform infrared spectroscopy, it was concluded that the composite material of CTS and MMT (CTS-MMT) was prepared successfully. The mass ratio of CTS to MMT had a strong influence on the adsorption performance of CTS-MMT. The highest adsorption value of 150mg/g was obtained over the composite material with CTS to MMT mass ratio of 0.25, which is much higher than those reported in other studies. The adsorption isotherms and kinetic results indicated that Co(2+) was adsorbed over CTS-MMT in a multilayer model, and the chemical sorption of Co(2+) was determined to be the rate-limiting step.

An amphiphilic polymer with anthracene pendants of PEO-b-PAM has been applied to comprehensively investigate the photodimerization characteristics of anthracene in aqueous solution upon various selected narrow band of light irradiations in the UV-vis-NIR region.

The effect of the acidity and topological structure of zeolites on the performance of the steam reforming of dimethyl ether (SRD) was comparatively investigated over the bifunctional catalyst composed of zeolite and Cu/ZnO/Al2O3 under the conditions of DME/H2O/N2 = 1/4/5, catalyst loading of 0.9 g, GHSV = 4000 mL g−1 h−1. The bifunctional catalyst was prepared by physically mixing Cu/ZnO/Al2O3 with H-ZSM-5 (Si/Al2O3 = 25), H-USY, and H-beta (Si/Al2O3 = 20), respectively. The acidic properties of the zeolite were characterized by NH3-TPD technique. Over all the bifunctional catalysts with a Cu/ZnO/Al2O3 to zeolite weight ratio of 1, SRD was dominantly occurred, and H-ZSM-5 based bifunctional catalyst showed the highest SRD performance, i.e., DME conversion of over 95% and H2 yield of about 80%. Moreover, light hydrocarbons were formed under SRD conditions as a result of DME (methanol) to hydrocarbons reactions (DTH, MTH). The results were well explained based on the two-step mechanism of SRD and the acidic properties of the zeolite. Unexpectedly, a white powdery product, which is determined to be hexamethyl benzene (HMB) by FT-IR, 1H and 13C NMR, GC/MS, and elemental analysis, was condensed at the outlet of the reactor when H-USY or H-beta based bifunctional catalysts were applied for SRD. Furthermore, the formation of HMB was more pronounced over the bifunctional catalyst by using H-beta as an acidic component. To the best of our knowledge, this is the first report on the formation of HMB under SRD conditions. Based on the results by changing the weight ratio of Cu/ZnO/Al2O3 to H-beta, the SRD mechanism, and the topological and acidic properties of H-beta, the formation of HMB was well explained as the side reactions of MTH and DTH and the larger channel sizes of zeolites Y and beta than that of the HMB molecules. Importantly, on the one hand, our findings can shed some lights on screening suitable solid acids for SRD. On the other hand, clear evidence is provided for the hydrocarbon pool mechanism of MTH reaction, and HMB is revealed to be the very possible species of hydrocarbon pool.

Ultraclean fuels production has become increasingly important as a method to help decrease emissions and allow the introduction of alternative feed stocks for transportation fuels. Established methods, such as Fischer-Tropsch, have seen a resurgence of interest as natural gas prices drop and existing petroleum resources require more intensive clean-up and purification to meet stringent environmental standards. This review covers some of the advances in deep desulfurization, synthesis gas conversion into fuels and feed stocks that were presented at the 245th American Chemical Society Spring Annual Meeting in New Orleans, LA in the Division of Energy and Fuels symposium on "Ultraclean Fuels Production and Utilization".