Cyclohexene Yield Research Articles

Selective regulation of products for guaiacol hydrodeoxygenation by adjusting type and acidity of supports

Upgrading lignin-oil into advanced fuels or chemicals has been widely studied in recent years. To understand the effect of support type and acidity on the hydrodeoxygenation (HDO) of guaiacol (lignin-oil model compound), Ni-based catalysts were prepared with SiO2, Al2O3 and ZSM-5 as supports, respectively. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption desorption, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Pyridine adsorption Fourier-transform infrared (Py-IR). The research results indicate that selective regulation of guaiacol hydrogenation products can be achieved by changing the type and acidity of support. Cyclohexanol is the main product over Ni/SiO2, while cyclohexane is the main product over Ni/ZSM-5 series catalysts. Moreover, as the Si/Al ratio increases, the catalytic activity of Ni/ZSM-5 slightly decreases, and the yield of cyclohexane also decreases. The Brønsted acidity of the support is the key to promoting the conversion of cyclohexanol to cyclohexane. The formation of NiAl2O4 is the main reason for the relatively low activity of Ni/Al2O3. The conversion of guaiacol is as high as 99.2 %, and the yield of cyclohexane is as high as 86.6 % over Ni/ZSM-5(Si/Al = 27). In addition, complete conversion of guaiacol and 92.6 % yield of cyclohexanol were achieved over Ni/SiO2. More importantly, Ni/SiO2 and Ni/ZSM-5(27) are suitable for aromatic substrates with different substituents, respectively.

Inhibiting effects during the co-conversion of lauric acid and anisole over Ni and NiMo catalysts

The co-hydroconversion of lauric acid and anisole was carried out over Ni and NiMo catalysts T=260 and 280 °C and pH2=40 bar. Ni/Al2O3 demonstrated a high activity in converting anisole to cyclohexane, but lauric acid conversion was suppressed over this catalyst. In the co-conversion of their mixture the phenolic had no effect on the conversion of the acid, but the latter prevented the cleavage of the C-O bond in both anisole and reaction intermediates. It was assumed that the successful conversion of anisole in its mixture with lauric acid required that a catalyst should provide the fast consumption of the acid component. Accordingly, NiMo/Al2O3 possessed a high activity in lauric acid conversion, and a high cyclohexane yield from anisole was observed after the complete consumption of the acid. The results of the present study can be useful for the rational design of a catalyst for the effective hydroconversion of bio-oil.

Tailored MgAl2O4 supported Ru catalyst for selective C–O bond cleavage in diphenyl ether hydrogenolysis

The direct cleavage of C−O bonds in lignin and its derivatives via hydrogenolysis is an essential reaction process for lignin conversion. Herein, we design a MgAl2O4 supported Ru catalyst using a facile and green method involving ball milling and microwave heating. The optimal catalyst, 0.5Ru/MgAl2O4, displayed enhanced catalytic performance for 4−O−5 linkage scission compared to 0.5Ru/Al2O3 and 0.5Ru/MgO, achieving a tuenover frequency of 352.9 h−1 for diphenyl ether (DPE) conversion. 0.5Ru/MgAl2O4 with low Ru loading achieved complete conversion of DPE, with 43.8% yield of cyclohexane (CHE) and 42.6% yield of cyclohexanol (CHL) after 2 h at 160 °C and 1.5 MPa H2. The promising catalytic activity can be attributed to the abundant electron-rich Ru0 species with high dispersion formed on MgAl2O4, derived from the strong electron transfer from the support to Ru. The reaction mechanism for the direct cleavage of the 4−O−5 bond, followed by phenyl ring hydrogenation, was confirmed by rigorous experiments. This work provides an inspiring idea for developing efficient heterogeneous catalysts for the utilization of lignin resources via hydrogenolysis.

Origin of the Increase in the Selectivity of Ru Catalysts with the Addition of Amines in the Presence of ZnSO4 for the Selective Hydrogenation of Benzene to Cyclohexene

The synthesis of nylon 6 and nylon 66 can be performed, starting with the selective hydrogenation of benzene to cyclohexene, which is deemed to be environmentally friendly and cost-saving and to have higher atom efficiency. Nano-Ru catalyst was synthesized via a precipitation method. The prepared catalyst was evaluated in the selective hydrogenation of benzene toward cyclohexene generation in the presence of ZnSO4 in a liquid batch reactor. The promotion effect of the addition of amines, i.e., ethylenediamine, ethanolamine, diethanolamine, and triethanolamine, was investigated. The fresh and spent catalysts were thoroughly characterized by XRD, TEM, AES, N2-sorption, FT-IR, and TPR. It was found that the addition of amines could significantly improve the catalytic selectivity toward cyclohexene formation in the presence of ZnSO4. This was attributed to the formation of (Zn(OH)2)5(ZnSO4)(H2O)x (x = 0.5, 3 or 4) through the reaction between ZnSO4 and the amines, which could be chemisorbed on the Ru surface. This led to retarding the formation of cyclohexane from the complete hydrogenation of benzene and, thus, increased the catalytic selectivity toward cyclohexene synthesis. Therefore, with the presence of ZnSO4, the amount of chemisorbed (Zn(OH)2)5(ZnSO4)(H2O)x increased with increasing amounts of added amines, leading to a decline in the catalytic activity toward benzene conversion and selectivity toward cyclohexene generation. When 7.6 mmol of diethanolamine and 10 g of ZrO2 were applied, the highest cyclohexene yields of 61.6% and 77.0% of benzene conversion were achieved over the Ru catalyst. Promising stability was demonstrated after six runs of catalytic experiments without regeneration. These achievements are not only promising for industrial application but also beneficial for designing other catalytic systems for selective hydrogenation.

High stable NiCoAl catalyst prepared by combustion method for the hydrodeoxygenation of lignin-derived phenolic compounds: Effect of calcination temperature

The hydrodeoxygenation of lignin-derived phenolic compounds holds great promise for biomass-derived liquid fuel production. However, achieving a consistently high cyclohexane yield poses a formidable challenge. In this study, NiCoAl catalysts were successfully synthesized using the solution combustion method for the hydrodeoxygenation of lignin-oil. The impact of calcination temperature on the preparation of NiCoAl catalysts was investigated. The results indicate that the selectivity of cyclohexane exhibits an initial increase followed by a decrease as the calcination temperature rises. Notably, the NiCoAl-600 catalyst reached 99.99% guaiacol conversion, with the highest selectivity of cyclohexane (97.96%) achieved. Characterization results demonstrate that the transition of the spinel structure from normal to inverse with rising calcination temperature. Moreover, the catalyst particle size initially decreases and then increases, while the oxygen vacancy concentration in the catalyst increases. It was found that these properties contribute to a better hydrodeoxygenation performances of guaiacol and other phenolic compounds over non-noble NiCoAl catalyst. Possible reaction pathway and mechanism are proposed and discussed. Additionally, the spinel-structured NiCoAl-600 catalyst has good thermal stability, ensuring potential application in the upgrading of lignin-oil.

Hydrodeoxygenation of mixtures of biomass-derived model compound oxygenates over Pt/HY catalysts

In this study, a systematic analysis of the effect of three biomass pyrolysis oxygenates, viz., acetic acid, cyclopentanone and furfural, on the hydrodeoxygenation (HDO) of guaiacol is performed. Bifunctional Pt/HY catalysts with different Si/Al ratios were screened for the HDO of guaiacol. Guaiacol conversion and the cyclohexane yield increased with the concentration of acid sites in the zeolites. The presence of acetic acid and cyclopentanone did not affect the guaiacol conversion and the product selectivity, while guaiacol conversion decreased significantly in the presence of furfural. The effects of temperature, reaction time, and the guaiacol-furfural molar ratio on the HDO of guaiacol were studied. The time evolution of products showed that the furan ring opening influences the conversion of guaiacol.Quantum chemicaldensity functional theorycalculations using individual and binary model compounds revealed the decrease in adsorption energy of guaiacol over Pt (111) in the presence of furfural.

Ru-Loaded Biphasic TiO2 Nanosheet-Tubes Enriched with Ti3+ Defects and Directionally Deficient Electrons as Highly Efficient Catalysts in Benzene Selective Hydrogenation

Crystalline phase engineering is a prominent strategy for synergistically optimizing the surface–body phases of a catalyst. In this work, TiO2 nanosheets assembled into nanotubes (TNSTs) with two phases, anatase and rutile, were firstly synthesized via crystal engineering by simple thermal annealing. These were subsequently loaded with Ru nanoparticles, with a mean size of 5.0 nm, to create the efficient benzene hydrogenation catalyst Ru/TNSTs. The well-designed nanosheet-tube structure boasts a large specific surface area and excellent transmission channels, which effectively prevents the agglomeration and deactivation of loaded Ru nanoparticles, as well as promoting the internal diffusion in the reaction process of benzene hydrogenation to cyclohexene. Furthermore, titanium dioxide nanosheet-tubes contain numerous Ti3+ defects, which not only improves the overall conversion rate of cyclohexene but also enhances the suppression of cyclohexene adsorption. Most importantly, the titanium dioxide with its two-phase composition of 75 wt% anatase and 25 wt% rutile increases the ratio of electron deficiencies of Ru and promotes cyclohexene desorption. These synergistic properties enhance the selectivity and efficiency of the Ru/TNSTs catalysts, resulting in excellent performance in the hydrogenation of benzene to cyclohexene. In particular, the Ru/TNSTs-4 catalyst (annealed for 4 h), under the specific conditions of 140 °C temperature and 5 MPa hydrogen pressure for the hydrogenation process, achieves a 95% initial selectivity and 51% yield of cyclohexene in the reaction, outperforming most supported Ru-based catalysts. This work may provide new perspectives for designing efficient benzene hydrogenation catalysts via crystalline phase engineering.

Fabricating Pt0-acid synergy in Pt/Beta phenol hydrodeoxygenation catalysts via a surface modification strategy of Beta molecular sieves

As for metal/zeolite supported phenol hydrodeoxygenation catalysts, it is important to improve the dispersion of metallic sites and build synergistic relationship between metallic and acid sites. The current research proposes a surface modification strategy by introducing CTAB in the NaOH etching of Beta. CTAB interacts with crystal defects to inhibit excessive crystal destruction. Aluminum atoms are protected from being removed and acid sites are reserved. Generated silicon hydroxyl groups anchor Pt0 particles. Pt0 particles are spatial resisted on the internal surface of catalysts to activate C–O bonds of phenol. Preserved acid sites provide reactive sites for dehydration reaction of cyclohexanol on the external surface of Pt/Beta-H. The high phenol conversion (i.e., 92.26 %) and cyclohexane yield (i.e., 7.18 %) were obtained at 80 °C due to the functional synergistic effect between acid and Pt0 sites. Proposed surface modification strategy proposes references for the structure design and development of efficient phenolics hydrodeoxygenation catalysts.

THE SCIENTIFIC BASIS OF INDUSTRIAL APPLICATION OF THE PROCESS OF SELECTIVE HYDROGENATION OF BENZENE IN DIFFERENT CATALYTIC SYSTEMS

Pollution of the environment with substances obtained in the production of oil and other products in various industries forces us to take measures to solve environmental problems that have become relevant in recent years. Arenes, belonging to the class of petroleum-derived aromatic hydrocarbons, are very life-threatening substances due to their carcinogenic effects. In this regard, one of the important issues is the release of benzene, a special representative of arenes, from its carcinogenic effect as a toxic and volatile compound, and its use in the production of cyclohexane, which is the main raw material for the production of caprolactam and nylon. The selectivity of the hydrogenation of benzene and the high yield of cyclohexane, the target product, depend on the reaction conditions and the choice of catalysts. In recent years, the application of polymer and zeolite nanocomposite catalysts, as well as modified metal polymer-based catalysts, in obtaining highly active and selective catalysts for the purpose of effective implementation of aromatic hydrocarbon hydrogenation processes is of great interest. Thus, naphthenic hydrocarbons are considered the main starting materials for the synthesis of various classes of compounds. Derivatives of these compounds are used in the pharmaceutical industry as special-purpose caprolactam, adipic acid, cyclohexanone, as a solvent for essential oils, varnishes, paints, as an extractant, etc. are used in synthesis. As a result of investigating the catalytic properties of polymer-mineral catalysts in the benzene hydrogenation reaction, it was determined that these reactions show selectivity in the direction of cyclohexane formation in narrow-pore zeolites (mordenite, clinoptilolite)In the presented work, the main information was collected by analyzing the literature on the work carried out in this direction

Efficient olefin epoxidation with high turnover rates over ordered mesoporous silica nanoparticles with uniform manganese sites

Olefin epoxidation has been studied over a series of mesoporous manganese silicate nanoparticles and tBuOOH. Partial substitution of Si by Mn in silica framework leads to highly dispersed, distorted Mn(III) sites, confirmed by various physicochemical analyses. High conversion and stable styrene oxide, stilbene oxide and epoxy cyclohexane yield have been achieved with MS75 with 1:1.5 ratio of olefin: oxidant. However, at faster reaction rates lower styrene oxide yield is observed at lower Mn-containing catalyst (MS100). High TON, TOF over manganese sites shows accessible monomeric Mn sites. Attributed to high reactant density at redox-active Mn silicate sites due to facile diffusion across shallow pore depth channels of nanoparticulate om-MSx and surface hydrophobic characteristics. The catalysts were found to be stable under recycling and filtration experiments. The excellent stability against leaching of active manganese species indicates stable sites and good textural properties in om-MSx, essential for extended activity.

STUDY OF THE LIQUID-PHASE HYDROGENATION OF BENZENE IN THE PRESENCE OF METAL-POLYMER COMPLEXES BASED ON POLYVINYLPYRIDINES

The liquid-phase hydrogenation of benzene on metal-polymer complexes, which were prepared on vinylpyridine polymers containing functional groups and salts of transition metals such as nickel, palladium, and platinum, was studied. Poly-4-vinylpyridine and poly-2-methyl-5-vinylpyridine were used as vinylpyridine polymers. Hydrogenation was carried at a temperature of 20-600 C. The study additionally focussed on the influence of the nature of the medium on the benzene hydrogenation process on poly-4-vinylpyridines. It has been established that in the presence of a platinum-poly-4-vinylpyridine complex, the reaction of liquid-phase hydrogenation of benzene, not only the product of complete hydrogenation, but also products of incomplete hydrogenation, cyclohexene, are formed. It was also found that the nature of the medium affects the yield of cyclohexane and cyclohexene selectively and effectively

Hydrodeoxygenation of phenol as a model compound by Ni2P/HBeta-SBA-15,

The stable silica sieve-based HBeta-SBA-15 catalyst-carrier was successfully prepared by a hydrothermal synthesis method, and then Ni2P/HBeta-SBA-15 new hydrodeoxygenation catalyst was successfully loaded by the equal volume impregnation method. It was characterized by X-ray diffraction (XRD), N2 adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and pyrolysis-infrared (Py-IR) methods. The results showed that SBA-15 was successfully immobilized on HBeta to form a microporous and mesoporous composite carrier. The introduction of SBA-15 not only increased the specific surface area of HBeta-SBA-15, but also reduced its acidity. After loading the active metal component Ni2P, the structure of the catalyst has not changed much. Hydrodeoxygenation (HDO) of phenol model compounds over Ni2P/HBeta-SBA-15 catalyst was studied in water. The response surface analysis showed that the conversion of phenol was 84.4% and the selectivity of cyclohexane was 94.2% at a lower temperature of 240 °C. The effect of reaction conditions on the yield of cyclohexane was as follows: the reaction temperature > the amount of hydrogen > the amount of catalyst > the reaction time. This study provides theoretical guidance for upgrading biomass pyrolysis oil to green fuel through hydrodeoxygenation.

Dynamics-driven tailoring of sub-nanometric Pt-Ni bimetals confined in hierarchical zeolite for catalytic hydrodeoxygenation

Metal-zeolite catalysts are promising for hydrodeoxygenation of bio-oils, but they always encounter sluggish diffusion kinetics due to sole micropores and inferior metal stability. Here, highly stable sub-nanoscale Pt-Ni bimetals confined in a hierarchical ZSM-5 zeolite (Pt-Ni@HZ) are constructed. The formed Pt-Ni@HZ species create framework-bonding metal sites with zeolite in a confined microenvironment, thereby establishing strong interactions and generating uniform distribution of Pt-Ni bimetals. In the Pt-Ni@HZ-catalyzed hydrodeoxygenation of phenolics, sub-nanometric Pt-Ni facilitates the adsorption and transfer of hydrogen, and hierarchical pores promote the diffusion kinetics of reactants. The designed Pt-Ni@HZ with small metal particles and high coordination numbers of Pt-Ni bonds, favors the complete deoxygenation of phenolics, with a higher yield of cyclohexane than conventional catalysts prepared by impregnation. Benefiting from the protection of the zeolite framework, the Pt-Ni@HZ catalyst exhibits high thermal stability and low leaching of metal active sites, with only 4.4 % catalyst deactivation after five reaction cycles.

Defect‐Decorated NiFe Bimetallic Nanocatalysts for the Enhanced Hydrodeoxygenation of Guaiacol

AbstractSeries of Ni‐based nanocatalysts were fabricated for the HDO of lignin‐derived guaiacol to cyclohexane via a single‐source Ni−Fe−Al layered double hydroxide precursor route and characterized by XRD, BET, TEM, XAS, XPS, H2‐TPR, H2‐TPD, NH3‐TPD, and pyridine absorbed in situ FT‐IR. As‐fabricated bimetallic NiFe nanocatalyst bearing a Fe/Ni molar ratio of 0.5 : 3 attained a higher cyclohexane yield of 70.5 % under mild reaction conditions (i. e., 230 °C and 1.0 MPa of initial hydrogen pressure), compared to monometallic Ni and other NiFe bimetallic nanocatalysts, as well as monometallic Ni and bimetallic NiFe catalysts prepared by the impregnation method. Combination of experimental results and density functional theory calculations manifested that interfacial FeOx species profoundly facilitated the demethoxylation processes of guaiacol and 2‐methoxycyclohexanol intermediate, while both bimetallic NiFe sites and interfacial FeOx species greatly promoted the dehydroxylation of cyclohexanol intermediate.

Regulating Surface‐Interface Structures of Zn‐Incorporated LiAl‐LDH Supported Ru Catalysts for Efficient Benzene Hydrogenation to Produce Cyclohexene

AbstractIn the heterogeneous catalysis, adsorption and desorption behaviors of reactants and products on the surface of catalysts can remarkably impact their catalytic activities and product selectivities. Here, series of Ru‐based catalysts supported on Zn‐incorporated Li−Al layered double hydroxides (Ru/LDH) were developed and employed in the selective benzene hydrogenation to produce cyclohexene without the use of any additional zinc salt additives. It was demonstrated that as‐constructed supported Ru catalyst bearing a Zn/(Li+Zn) molar ratio of 0.075 in the LDH support gave a higher cyclohexene yield of 43.2 % than those over other Ru‐based ones. Combining structural characterizations and catalytic hydrogenation reactions with temperature‐programmed desorption and in situ Fourier transform infrared spectroscopy of benzene and cyclohexene, it was revealed that the generation of appropriate surficial/interfacial Ru0/Ruδ+−O−Zn structures, as well as the existence of abundant hydroxyl groups on LDH supports, could facilitate the benzene adsorption and the cyclohexene desorption, thereby remarkably promoting the formation of cyclohexene. The present findings not only give a profound insight into the roles of surface‐interface structures of supported Ru catalysts for efficient benzene hydrogenation to produce cyclohexene but also simultaneously provide a promising guide to design high‐performance Ru‐based catalysts.

Synthesis of uniform Ni nanoparticles encapsulated in ZSM–5 for selective hydrodeoxygenation of phenolics

Bio–oil as the promising renewable resources to replace fossil fuels, requires upgrading into deoxygenated fuel. Zeolite supported base metal catalysts have been deemed highly efficient for the hydrodeoxygenation (HDO) of bio–oil, but facing a degraded activity due to metal aggregation. In this study, uniform Ni nanoparticles (∼4 wt%) encapsulated in ZSM–5 zeolites (Ni@ZSM–5s) were synthesized by a one–pot method for catalytic HDO of phenolic compounds. The Ni dispersion was found to be significantly enhanced in the Ni@ZSM–5s catalysts after encapsulation compared with a catalyst prepared by wetness impregnation (Ni/ZSM–5), which is ascribed to the strong interaction between the Ni and the zeolite surface. The Ni@ZSM–5s catalysts show higher HDO activities for phenolics than the Ni/ZSM–5 catalyst, owing to the enhanced adsorption and spillover of active hydrogen by the highly dispersed Ni species. Ni@ZSM–5–50 (Si/Al of 50) gave cyclohexane yield of 91.6% at 250 °C, through sequenced hydrogenation and deoxygenation of anisole. Moreover, the Ni@ZSM–5–100 (Si/Al of 100) with decreased acidities further gave an enhanced TOF value for the conversion of phenolics. From the FT–IR spectrum obtained for adsorbed anisole, the reduction of acidities is determined to facilitate the desorption of intermediates, which accelerates the initial hydrogenation.

Fabricating Bifunctional Co−Al2O3@USY Catalyst via In‐Situ Growth Method for Mild Hydrodeoxygenation of Lignin to Naphthenes

AbstractTo enhance the catalytic activity and stability of metal catalysts in the hydrodeoxygenation of lignin derivatives into naphthenes, a bifunctional Co−Al2O3@USY catalyst was fabricated by the reduction of CoAl layered double hydroxide in‐situ grown on the USY zeolite. In the hydrodeoxygenation of guaiacol, a 100.0 % conversion with cyclohexane yield up to 93.6 % was achieved at 180 °C, 3 MPa for 4 h, which should be the hitherto lowest reaction temperature that has been reported over Co‐based metal catalysts. This catalyst was also relatively stable with 5 runs and exhibited excellent catalytic performance in the hydrodeoxygenation of other lignin model compounds and even real lignin feedstock into naphthenes. The high‐efficiency of Co−Al2O3@USY was attributed to the synergistic effect between well‐dispersed small Co nanoparticles and abundant acidic sites on the USY surface, while the outstanding stability was attributed to the anchoring effect of Al2O3 matrix to Co nanoparticles which avoided the leaching of Co species and particle agglomeration. This work provides a potential strategy for the design of an efficient and stable catalyst for lignin utilization.

Synergies of surface-interface multiple active sites over Al-Zr oxide solid solution supported nickel catalysts for enhancing the hydrodeoxygenation of anisole

Currently, the catalytic hydrodeoxygenation (HDO) of oxygen-containing compounds derived from biomass to highly valuable chemicals or hydrocarbon bio-fuels is attracting more and more attention. Concerning the design and synthesis of high-performance supported metal catalysts for HDO, the efficient deposition/immobilization of active metal species on supports, as well as the construction of the favorable properties of supports, is quite necessary. In this work, we fabricated series of aluminum-zirconium oxide solid solution supported Ni-based catalysts by a simple surfactant-assisted homogeneous coprecipitation and applied them in the HDO of anisole. Various structural characterizations showed that surface-interface properties of Ni-based catalysts (i.e., surface acidity, defective structures, and metal-support interactions) could be finely tuned by adjusting the amount of Al introduced into Al-Zr oxide solid solutions, thus profoundly governing their catalytic HDO activities. It was demonstrated that the introduction of an appropriate amount of Al could not only enhance surface acidity and promote the formation of defective Zr-Ov-Al structures (Ov: oxygen vacancy) but also facilitate the generation of interfacial Niδ+ species bound to the support. Over the Ni-based catalyst bearing an Al2O3:ZrO2 mass ratio of 5:2, a high cyclohexane yield of ∼77.4% was attained at 230 °C and 1.0 MPa initial hydrogen pressure. The high catalytic HDO efficiency was revealed to be correlated with the catalytic synergy between Ni0 and adjacent interfacial Niδ+ species, together with the promotion of neighboring defective oxygen vacancies and acidic sites, which contributed to the enhanced activation of the methoxy group in anisole and reaction intermediate and thus greatly improved HDO activity. The present findings offer a new and promising guidance for constructing high-performance metal-based catalysts via a rational surface-interface engineering.

Mild hydrodeoxygenation of lignin-derived bio-oils to hydrocarbons over bifunctional ZrP2O7-Ni12P5 catalysts

An imperative current challenge for the production of renewable fuels is the development of efficient catalytic hydrodeoxygenation (HDO) of phenolic-rich bio-oils into hydrocarbons. In this work, a series of bifunctional ZrP2O7(x)-Ni12P5 (where × represents the molar ratio of Zr/Ni in the catalysts) catalysts were prepared for HDO of lignin-derived bio-oils (LBO). The characterization results show that among these bimetallic catalysts, ZrP2O7(0.4)-Ni12P5 possesses the largest specific surface area, pore volume and the highest amount of acid sites (Lewis and Brønsted) due to the introduction of appropriate amount of Zr species. Meanwhile, the interaction between Niδ+ and Zr species on its surface creates new active sites for the promotion on the hydrogen adsorption and activation, thus endowing the most excellent catalytic performance. Using the optimized catalyst of ZrP2O7(0.4)-Ni12P5, 95.8% cyclohexane yield could be obtained from the HDO of guaiacol as a model compound from bio-oil under mild condition (3 MPa H2 and 250 ℃). Moreover, 36.1% hydrocarbon yield is achieved from HDO of lignin-derived bio-oils (LBO) under the same hydrogen pressure and temperature. These findings not only open a novel avenue for designing a cost-effective metal–acid bifunctional catalyst, but also provide a viable approach for converting lignocellulosic biomass feedstocks into valuable hydrocarbons.

Hydrogenation of cyclohexene catalyzed by nanoporous SPE-PtNi/C membrane electrode

Implementing large-scale synthesis of nanoporous PtNi/C catalysts for hydrogenation processes of unsaturated organic compounds under atmospheric pressure at temperatures below 100 °C is an urgent task. In this paper, a nanoporous SPE-PtNi/C membrane electrode is prepared by ion beam sputtering, ultrasonic-assisted electrochemical dealloying, and hotpressing. Special attention is paid to the analysis of the electrochemical properties, phase structure, surface morphology, active constituent distribution, and catalytic efficiency for cyclohexene hydrogenation of the produced electrode in comparison with those of commercial Pt/C catalysts. The results show that the ultrasonic-assisted electrochemical etching temperature exerts the most significant effect on the catalytic activity of the catalyst under consideration. In particular, the treatment of PtNi/C in 0.7 mol/L HClO4 for 1.5 h at the optimized temperature of 50 °C enables one to increase the catalytic activity by 25.20% at decreasing the Pt-loading content by 88.85% compared with commercial Pt/C. Furthermore, the nanoporous structure of the PtNi/C surface allows the binding energy of Pt 4f7/2 to be reduced by 0.23 eV due to the Ni loss and the crystal plane shrinkage from NiPt, which enhances the compressive strain of the lattice structure of exposed Pt and increases the number of active sites. Finally, the use of a nanoporous SPE-PtNi/C membrane electrode could increase the yield of cyclohexene during the hydrogenation reaction by 179% at simultaneously improving the current efficiency by 69%.