Cyclohexene Yield Research Articles

Effect of ZnSO4, MnSO4 and FeSO4 on the Partial Hydrogenation of Benzene over Nano Ru-Based Catalysts.

Nano Ru-based catalysts, including monometallic Ru and Ru-Zn nanoparticles, were synthesized via a precipitation method. The prepared catalysts were evaluated on partial hydrogenation of benzene towards cyclohexene generation, during which the effect of reaction modifiers, i.e., ZnSO4, MnSO4, and FeSO4, was investigated. The fresh and the spent catalysts were thoroughly characterized by XRD, TEM, SEM, XPS, XRF, and DFT studies. It was found that Zn2+ or Fe2+ could be adsorbed on the surface of a monometallic Ru catalyst, where a stabilized complex could be formed between the cations and the cyclohexene. This led to an enhancement of catalytic selectivity towards cyclohexene. Furthermore, electron transfer was observed from Zn2+ or Fe2+ to Ru, hindering the catalytic activity towards benzene hydrogenation. In comparison, very few Mn2+ cations were adsorbed on the Ru surface, for which no cyclohexene could be detected. On the other hand, for Ru-Zn catalyst, Zn existed as rodlike ZnO. The added ZnSO4 and FeSO4 could react with ZnO to generate (Zn(OH)2)5(ZnSO4)(H2O) and basic Fe sulfate, respectively. This further benefited the adsorption of Zn2+ or Fe2+, leading to the decrease of catalytic activity towards benzene conversion and the increase of selectivity towards cyclohexene synthesis. When 0.57 mol·L−1 of ZnSO4 was applied, the highest cyclohexene yield of 62.6% was achieved. When MnSO4 was used as a reaction modifier, H2SO4 could be generated in the slurry via its hydrolysis, which reacted with ZnO to form ZnSO4. The selectivity towards cyclohexene formation was then improved by the adsorbed Zn2+.

Upgrading bio-oil model compound over bifunctional Ru/HZSM-5 catalysts in biphasic system: Complete hydrodeoxygenation of vanillin

A complete hydrodeoxygenation(HDO) of vanillin to yield cycloalkanes was performed using bifunctional Ru loaded HZSM-5 catalysts with different metal loadings (0.1, 0.5, 1, 3, and 5 wt%) and Si/Al2 ratios (Si/Al2 = 23,300) in n-octane/water biphasic system. Both the reaction pathway and product distribution were influenced by the metal/acid balance of the catalysts. Higher metal/acid ratio promoted Caryl-C cleavage reaction, resulting in the increased yield of cyclohexane. Synergetic effect of metal and acid sites was observed in the bifunctional catalyst, attaining as high as 40-fold increase of metal efficiency in the ring hydrogenation reaction, compared to lone metal site catalyst. The effect of solvent composition was evaluated, revealing that the presence of water promoted the overall HDO reaction. By balancing metal/acid and introducing appropriate solvent system, efficient catalytic system that minimized carbon loss and improved metal efficiency for vanillin HDO was obtained.

Hydrodeoxygenation of phenol and pyrolysis oil using Raney Ni and IL/Zr-SBA-15 catalysts

A novel IL/Zr-SBA-15 (n(Si)/n(Zr)= 2,10,40) catalysts were synthesized, and characterized by XRD, FTIR, SEM, TEM, N2 adsorption–desorption measurement and DSC/TG. The results showed that ionic liquid (IL) has been successfully immobilized on the surface of Zr-SBA-15, and the ordered mesoporous structure can also be well preserved, even after chemical grafting reaction. Using water as a solvent, Raney Ni and IL/Zr-SBA-15 composite catalysts were investigated by hydrodeoxygenation (HDO) of phenol. The synergy of acid and metal catalysts can effectively catalyze phenol as a model compound for pyrolysis oil by tandem reactions. Under optimum reaction condition, the mean selectivity and yield of cyclohexane was 81.08% and 76.26%, respectively. The catalyst still provided satisfactory results after 5 runs. With reference to the study of phenol, HDO was carried out on the coconut clothes pyrolysis oil. The process conditions were optimized by response surface methodology. In addition, it is concluded that reaction conditions affect the order of naphthenes component content as reaction temperature>reaction time>hydrogen pressure. As a result, the content of naphthenes components in the bio-fuel reaches 34.43% and the HHV of 37.58 MJ/kg, indicating that this catalyst also has a good effect on HDO of the pyrolysis oil.

Structure-tunable pompon-like RuCo catalysts: Insight into the roles of atomically dispersed Ru-Co sites and crystallographic structures for guaiacol hydrodeoxygenation

Currently, the highly efficient conversion of biomass resources into highly valuable chemicals and biofuels is one of the most prospective approaches to reduce greenhouse gases emission and environmental pollution caused by excess consumption of fossil fuels. Herein, three-dimensional pompon-like well-defined RuCo particles with tunable crystallographic structures and surface atomically dispersed Ru atoms were constructed and intensively investigated as support-free metal catalysts in the hydrodeoxygenation (HDO) of lignin-derived guaiacol. It was demonstrated that the 300 °C-reduced RuCo sample possessed the hexagonal close-packed (hcp) crystallographic structure with surface abundant atomically dispersed Ru atoms, whereas 600 °C-reduced RuCo sample presented the face-centered cubic phase with lower surface Ru concentration. The as-fabricated RuCo-300 sample showed excellent catalytic HDO activity with a high cyclohexane yield of 85.3%. Comprehensive structural characterizations unveiled that the introduction of atomically dispersed Ru atoms into the RuCo-300 favored the formation of abundant surface Ru-Co sites, as well as electron-rich Ru0, and such-constructed Ru-Co sites were highly beneficial to the hydrogen dissociation on single Ru0 atoms and the further hydrogen spillover to adjacent Co0 atoms to promote the HDO process. Moreover, density functional theory (DFT) calculations revealed that the hcp structure of RuCo catalysts benefited the adsorption of guaiacol. The unique pompon-like microstructure of RuCo catalysts was conducive to the exposure of active sites and provided more open channels for the easy diffusion of reactants and products. Over the RuCo-300 catalyst, the guaiacol HDO could proceed rapidly via an initial demethoxylation reaction. The present Ru-Co synergetic catalysis in the structure of RuCo catalysts would provide a new strategy for constructing robust heterogeneous bimetal catalysts applied in practical HDO processes of a variety of lignin-derived phenolic compounds.

Ru/Hβ catalyst prepared by the deposition-precipitation method for enhancing hydrodeoxygenation ability of guaiacol and lignin-derived bio-oil to produce hydrocarbons

Recently hydrocarbons with high yield from the selective hydrodeoxygenation (HDO) of lignin-derived bio-oil under low temperature still encounters the great challenges. However, metal nanoparticles size and acid site can greatly influence the HDO activity of metal catalyst. Herein, the efficient bifunctional Ru/Hβ catalyst was prepared by modified deposition-precipitation (DP) method for the HDO reaction of guaiacol and catalytic isoproanolysis lignin-derived bio-oil. Notably, compared to the impregnated Ru3%/Hβ-25 catalyst, Ru3%/Hβ-25 (DP) catalyst exhibited the higher catalytic activity on the HDO of guaiacol, smaller Ru nanoparticles size, and more acid sites. It was observed that guaiacol can be completely converted to cyclohexane under 180 °C, 3 MPa H2, and 2 h in n-hexane. This Ru3%/Hβ-25 (DP) catalyst proved to be the good recyclability in the HDO reaction of guaiacol, the conversion decreased slightly to 82.3% and the yield of cyclohexane decreased to 71.2 mol% after four recycle times. Furthermore, this high active catalyst was also applied to the upgradation of bio-oil derived from the catalysis isoproanolysis of lignin in the organic phase. As a result, after the upgradation, bio-oil contained high relative content (RC) of hydrocarbons, including 42.99% cycloalkanes and 50.74% arenes, and oxygenated compounds of raw bio-oil were almost removed. Overall, during upgradation of raw lignin-derived bio-oil over Ru3%/Hβ-25 (DP) catalyst process, not only HDO reaction, but also cleavage of C-O bonds can be achieved in one-pot.

Selective hydrogenation of benzene over Ru supported on surface modified TiO2

A series of catalysts with ruthenium nanoparticles (NPs) loaded on the binary oxide TS (TiO2-SiO2) support were prepared by facile sol-gel method for benzene selective hydrogenation. Different mole ratios of Ti/Si were investigated. The catalytic structure, composition, hydrophilicity, electronic state and acidity were characterized. The results indicate that the acidity of the samples increases gradually with the increase of the SiO2 amount. The dispersion of ruthenium nanoparticles was improved on binary oxide support compared with TiO2 and an obvious Ru size effect appeared with the increase of Ti/Si molar ratio. It was also found that the hydrophilicity of the supports could be efficiently improved by introducing a small amount of SiO2 to TiO2, which may be due to the large amount of surface hydroxyl groups on the binary oxide samples after SiO2 introduction. This result was consistent with the increasing trend of cyclohexene yield, indicating that the surface hydroxyl groups play a significant role in the motivation of cyclohexene desorption. Ru/TS (7: 1) showed the best catalytic performance of 38.2% yield to cyclohexene with the highest initial selectivity to cyclohexene (S0) of 87.3%. The catalytic stability experiments showed that the yield of cyclohexene could maintain at 30% after five cycles.

Ordered macroporous Co3O4-supported Ru nanoparticles: A robust catalyst for efficient hydrodeoxygenation of anisole

A three-dimensional ordered macroporous Co3O4 (OM-Co3O4) supported Ru catalyst was developed for the efficient hydrodeoxygenation (HDO) of anisole. It is revealed that small-sized Ru nanoparticles evenly distributed over the surface of OM-Co3O4 with large quantities of oxygen vacancies could strongly capture Ru0 species, thereby resulting in strong Ru-Co3O4 interactions. Compared with commercial Co3O4 supported Ru catalyst, Ru/OM-Co3O4 displays a better catalytic HDO performance, with a high cyclohexane yield of 92.4% at 250 °C and 0.5 MPa hydrogen pressure after 5 h on stream. Such a significant efficiency of Ru/OM-Co3O4 is mainly attributed to both high dispersion of Ru0 species and an enhanced formation of surface defects, as well as the unique macroporous framework of OM-Co3O4 support.

Hydrogenation of Toluene to Methyl Cyclohexane over PtRh Bimetallic Nanoparticle-Encaged Hollow Mesoporous Silica Catalytic Nanoreactors.

PtRh bimetallic nanoparticle (NP)-encaged hollow mesoporous silica nanoreactors (PtRh@HMSNs) are prepared by employing metal-ion-containing charge-driven polymer micelles as templates. These nanoreactors feature ∼1–2 nm PtRh NPs in ∼11 nm hollow cavities of HMSNs. Among various PtxRhy@HMSNs, Pt0.77Rh1@HMSNs show the best catalytic performance for toluene hydrogenation. Under 30 °C, atmospheric H2 pressure, and a toluene/(Pt+Rh) molar ratio of 200/1, Pt0.77Rh1@HMSNs reach 100.0% of methyl cyclohexane yield and demonstrate a much better catalytic performance than monometallic Pt@HMSNs and Rh@HMSNs and their physical mixtures. Moreover, Pt0.77Rh1@HMSNs exhibit a good catalytic stability during recycling experiments. The enhanced performance of Pt0.77Rh1@HMSNs is ascribed to the interaction between Pt and Rh, the beneficial effect of the relatively large mesoporous channels for mass transfer, as well as the confinement effect of functional NPs inside hollow cavities.

Influence of cadmium on Ru/xCd/Al2O3 catalyst for benzene partial hydrogenation

The thermodynamic of the partial hydrogenation of benzene with ruthenium catalyst drives the reaction to the cyclohexane formation. To stop the reaction in cyclohexene, promoters such as zinc are added. In this work, we carried out a preliminary DFT study showing that the addition of cadmium to a structure containing Ru and Al could be as effective or better than zinc in promoting partial hydrogenation of benzene. Experimentally, Ru/Al2O3 catalysts with 1% Ru and different cadmium contents were prepared by successive impregnations of CdCl2 and RuCl3 and characterized by textural analysis, XRD, EDXRF, SEM-EDS, DRS, TPR and H2-chemisorption. The catalysts were subjected to partial hydrogenation of benzene in batch reactor at 150 °C and 50 bar H2. The catalysts presented RuO2 and RuCl3 in function of the remaining chlorine content after calcination. The Ru0.2CdAl catalyst with Cd:Ru ratio 0.2:1 presented 2-fold higher activity and cyclohexene yield than Ru/Al2O3 without cadmium. This catalyst presented highest reducibility with Ruo, Ru-Cd interaction and higher H2 chemisorption. Additionally, a reaction with benzene and water showed that the Ru0.2CdAl catalyst obtained twice the activity of the same catalyst with pure benzene.

Role of metal support during ru-catalysed hydrodeoxygenation of biocrude oil

Hydrodeoxygenation (HDO) of guaiacol (a lignin-derived species) and biocrude oil was studied in a batch-type reactor operating at 4.0 MPa hydrogen over a series of Ru-based catalysts. Ru/BEA and Ru/ZSM-5, with varying Si/Al ratios, were investigated to examine the effect of pore size and acidity of supports on HDO of guaiacol and biocrude oil. In addition to this, large pore Ru/Al2O3 (possessing weak acid sites, 9.2 nm) and Ru/SiO2 (absence of acid sites, 15.2 nm) were also prepared and examined.It was observed that a decrease in the Si/Al ratio of the support results in an increase in the yield of cyclohexane and a decrease in the yield of 2-methoxycyclohexanol in HDO of guaiacol. This data also discloses the influence of the concentration of acid sites on the deoxygenation of 2-methoxycyclohexanol. Both Ru/BEA and Ru/ZSM-5, with both possessing low Si/Al ratios, display a high activity for HDO for guaiacol, while only the Ru/BEA catalyst exhibits a high activity for HDO of biocrude oil.Catalyst characterisation (BET, NH3-TPD and NH3 and acetonitrile-d3-FTIR) shows that the Ru/BEA catalyst, with a low Si/Al ratio, not only possesses strong Brønsted acid sites but also contains extensive mesoporosity. Notably, these mesopores appear to facilitate the hydrogenation, deoxygenation, and ring-opening of large oxygenated and condensed-ring hydrocarbons in biocrude oil which then leads to a high yield of cycloalkanes. As expected, the Ru/Al2O3 and Ru/SiO2 catalysts exhibit a high hydrogenation activity but a lower deoxygenation activity in the HDO of guaiacol and biocrude oil.These results suggest that the larger pore support, with strong Brønsted acid sites, engendered the HDO activity observed. The reaction pathway for the main components of biocrude oil was proposed based on the observed reaction product distribution.

High-Performance Evolution of Ni2P@Hierarchical HZSM-5 as the Guaiacol Hydrodeoxygenation Catalyst.

Hydrodeoxygenation (HDO) is one of the effective methods to upgrade biomass pyrolysis oil, but the development of a low-cost, high-performance HDO catalyst still faces enormous challenges. In this work, a facile and eco-friendly approach is developed to synthesize the Ni2P@hierarchical HZSM-5 catalyst. Structure and acidity of the catalyst can be controlled by simply adjusting the proportions of ammonia solution and the silicon to aluminum ratio, which are closely related to the performance of the catalyst. Experimental results reveal that the Ni2P@hierarchical HZSM-5 catalyst with Si/Al = 85 under NH3·H2O/Ni = 14 exhibits the highest activity of 98% guaiacol conversion, along with a 78.8% yield of cyclohexane (reaction conditions: 300 °C, 3 MPa H2). In addition, the guaiacol reaction network is provided.

Hydrodeoxygenation of guaiacol into cyclohexane over mesoporous silica supported Ni–ZrO2 catalyst

Abstract Ordered mesoporous silica SBA-15 and KIT-6 supported Ni/ZrO2 catalysts are evaluated for the hydrodeoxygenation of guaiacol (stirred batch reactor, 300 °C, 50 bar of H2), guaiacol being a model compound of bio-oil issued from the lignin fraction of biomass liquefaction. ZrO2 and Ni are dispersed using incipient-wetness impregnation (IWI) or two-solvent (TS) method over mesoporous silica. Mesoporous zirconia (nanocasting method) and conventional zirconia were also used as supports. Cyclohexane, cyclohexanol and methoxycyclohexanol are the main products of reaction. Significant differences in cyclohexane yield are measured (after 8 h reaction, with conversion in most cases above 85%): NiZr-KIT-TS, 71.6% > NiZr-SBA-TS, 63.3% ≫ Ni/meso-Zr, 7.8% > NiZr-SBA-IWI, 5.2% > Ni/ZrO2, 1.6%. Tetragonal ZrO2 phase, acting as oxophilic phase for guaiacol/oxygenated intermediates adsorption and activation, is observed whatever the approach selected for the preparation. However, when nickel is supported over pure zirconia, low selectivity to cyclohexane is obtained, while the main product becomes cyclohexanol with yields reaching ~40%. Better activities and selectivities toward total deoxygenation (cyclohexane production) are obtained for the silica supported Ni–ZrO2 catalysts, especially when the catalyst is prepared by the two-solvent approach. Improvement is associated to the proximity between Ni and ZrO2 particles when confined in the silica mesopores. Finally, conversion and yield to cyclohexane obtained with NiZr-KIT-TS are stable during 5 successive catalytic cycles demonstrating the absence of significant modification of the catalyst during reaction. These results are evidencing that the confining strategy is efficient to improve stability of active elements during HDO reaction.

Study on Catalyst Deactivation During the Hydrodeoxygenation of Model Compounds

To address the pressures associated with an increasing energy demand and rising cost of liquid fuel production, alternative feedstocks are being developed. One such potential replacement is bio-oils, which are derived from biomass, however the oil produced is often chemically unstable, corrosive and has low heating values due to the high oxygen content. Thus, an upgrading process is required to lower the oxygen content, with catalytic hydrodeoxygenation being one such technology currently being developed, with mechanistic studies commonly completed utilising model compounds. The current study examines factors that influence catalyst deactivation during hydrodeoxygenation of common bio-oil model compounds over zeolite-supported nickel catalysts, indicating the contribution of functional groups on the formation of condensed-ring products and catalyst deactivation. It was determined that phenolic-hydroxyl groups present in model compounds can facilitate catalyst deactivation through the formation of condensed-ring compounds, identified through decreased cycloalkane yields, causing blockage of catalyst pores. Conversely, when toluene, cyclohexanol and anisole were used as model compound feeds, there were no notable changes in cycloalkane yields, indicating aromatic, alkyl–OH and aromatic–OCH3 have negligible effect on catalyst deactivation. The effect of catalyst metal loading was also examined, and while increased metal content enhanced cyclohexane yields, so to was the formation of condensed-ring products, suggested to be the result of an increased concentration of surface cyclohexane carbocations. Modifications to reaction conditions was studied, with catalyst activity and stability found to improve with increasing reaction temperatures up to 230 °C. Based on the product distributions observed, a coupling reaction pathway (leading to the formation of condensed-ring products and cycloalkanes) is proposed as the hydrodeoxygenation mechanism.

Hydrodeoxygenation of Lignin‐Derived Monomers and Dimers over a Ru Supported Solid Super Acid Catalyst for Cycloalkane Production

AbstractThe monomers and dimers produced via lignin depolymerization are a promising alternative to transportation fuels after hydrodeoxygenation (HDO). However, these compounds contain numerous oxygen‐containing functional groups that are strongly bonded to aromatic rings. Therefore, the conventional HDO of lignin‐derived compounds faces serious problems of catalyst deactivation due to coke deposition and low hydrocarbon yields. A metal–solid super acid catalyst, i.e., Ru(SO42−)/ZrO2–CeO2, is synthesized, characterized, and evaluated for the HDO of various lignin‐derived monomers and dimers in a biphasic n‐dodecane/H2O system. A high cyclohexane yield of 98.5% is obtained by the HDO of phenol performed at 200 °C and 5 MPa. The “hydrated” configuration can be formed between the hydrogenation intermediates and H2O on the Ru sites. In addition, the anionic vacancies of ZrO2–CeO2 can be occupied by H− derived from the heterolytic cleavage of H2, leading to the formation of metal hydrides. The strong acidity of SO42−/ZrO2–CeO2 is beneficial for the subsequent deoxygenation of the hydrotreated products. In addition, the biphasic system can minimize the side reactions induced by the strong acidity of the catalyst. The catalytic system also exhibits a good catalytic performance for the HDO of other lignin‐derived monomers and dimers to produce cycloalkanes.

Development of the hierarchical ETS-10 zeolite catalyst for improving the aqueous-phase biomass hydrodeoxygenation activity

An imidazolium-based ionic liquid (IL) was employed and modified by sodium lignosulfonate (LnNa) to synthesize hierarchical ETS-10 zeolite with porous structure, morphology and surface properties effectively adjusted. The template and structure-directing effects of both IL and LnNa proved to be well maintained after modification. And more importantly, the unique molecular recognition of LnNa was preserved well, while the aggressiveness of LnNa implementing through interaction with other inorganic species can be efficiently suppressed. This led to the formation of hierarchical ETS-10 zeolite with not only high crystallinity and structure integrity but also enhanced catalytic performance in aqueous-phase biomass conversion. Thus, for guaiacol hydrodeoxygenation, a notable conversion (92.8%) and cyclohexane yield (89.7%) can be acquired. This remarkable catalytic reactivity should be owing to its distinguished analogous molecular recognition pattern, promoted crystallinity, modified morphology and porous structure, and what’s more, the strengthened acid property.

Investigation on Mn3O4 Coated Ru Nanoparticles for Partial Hydrogenation of Benzene towards Cyclohexene Production Using ZnSO4, MnSO4 and FeSO4 as Reaction Additives.

Mn3O4 coated Ru nanoparticles (Ru@Mn3O4) were synthesized via a precipitation-reduction-gel method. The prepared catalysts were evaluated for partial hydrogenation of benzene towards cyclohexene generation by applying ZnSO4, MnSO4 and FeSO4 as reaction additives. The fresh and spent catalysts were thoroughly characterized by XRD, X ray fluorescence (XRF), XPS, TEM and N2-physicalsorption in order to understand the promotion effect of Mn3O4 as the modifier as well as ZnSO4, MnSO4 and FeSO4 as reaction additives. It was found that 72.0% of benzene conversion and 79.2% of cyclohexene selectivity was achieved after 25 min of reaction time over Ru@Mn3O4 with a molar ratio of Mn/Ru being 0.46. This can be rationalized in terms of the formed (Zn(OH)2)3(ZnSO4)(H2O)3 on the Ru surface from the reaction between Mn3O4 and the added ZnSO4. Furthermore, Fe2+ and Fe3+ compounds could be generated and adsorbed on the surface of Ru@Mn3O4 when FeSO4 is applied as a reaction additive. The most electrons were transferred from Ru to Fe, resulting in that lowest benzene conversion of 1.5% and the highest cyclohexene selectivity of 92.2% after 25 min of catalytic experiment. On the other hand, by utilizing MnSO4 as an additive, no electrons transfer was observed between Ru and Mn, which lead to the complete hydrogenation of benzene towards cyclohexane within 5 min. In comparison, moderate amount of electrons were transferred from Ru to Zn2+ in (Zn(OH)2)3(ZnSO4)(H2O)3 when ZnSO4 is used as a reaction additive, and the highest cyclohexene yield of 57.0% was obtained within 25 min of reaction time.

One-Pot Conversion of Lignin into Naphthenes Catalyzed by a Heterogeneous Rhenium Oxide-Modified Iridium Compound.

The direct transformation of lignin into fuels and chemicals remains a huge challenge because of the recalcitrant and complicated structure of lignin. In this study, rhenium oxide-modified iridium supported on SiO2 (Ir-ReOx /SiO2 ) is employed for the one-pot conversion of various lignin model compounds and lignin feedstocks into naphthenes. Up to 100 % yield of cyclohexane from model compounds and 44.3 % yield of naphthenes from lignin feedstocks are achieved. 2 D HSQC NMR spectroscopy before and after the reaction confirms the activity of Ir-ReOx /SiO2 in the cleavage of the C-O bonds and hydrodeoxygenation of the depolymerized products. H2 temperature-programmed reduction, temperature-programmed desorption of NH3 , IR spectroscopy of pyridine adsorption, X-ray photoelectron spectroscopy, X-ray absorption fine structure analysis, and control experiments reveal that a synergistic effect between Ir and ReOx in Ir-ReOx /SiO2 plays a crucial role in the high performance; ReOx is mainly responsible for the cleavage of C-O bonds, whereas Ir is responsible for hydrodeoxygenation and saturation of the benzene rings. This methodology opens up an energy-efficient route for the direct conversion of lignin into valuable naphthenes.

Hydrodeoxygenation of 2-methoxy phenol: Effects of catalysts and process parameters on conversion and products selectivity

The hydrodeoxygenation (HDO) of 2-methoxy phenol (MP), a lignin-derived compound, has massive prospective for valuable compounds production. The lignin derived model compounds can be used for production of green chemicals. The model compound MP conversion into cyclohexane was investigated over Ru metal loaded on various supports (ZSM-5, Y-zeolite, β-zeolite, COK-12, mordenite, ZrO2, and TiO2). The catalytic properties such as the acidic sites, pore size, and morphology influenced the HDO activity and selectivity of the cyclohexane. The yield of cyclohexane increases up to optimum acidity further increases the acidity of the catalyst, the product yield decreased. The experiments carried out at temperature range of 200–300 °C, and 1–25 bar hydrogen pressure in a fixed bed reactor. The parameters greatly influenced the HDO as well as the cyclohexane yield, selectivity, and MP conversion. The highest conversion (100%) and yield of cyclohexane (99.0%) observed at 250 °C under pressure of 20 bar with Ru/ZSM-5 catalyst. Further the recyclability and stability have been checked and observed that Ru/ZSM-5 is stable up to 200 h and displayed excellence activity in both HDO and cyclohexane selectivity. Weight hourly space velocity (WHSV) was investigated (0.5–1.5 h−1). The suitable WHSV found for HDO of 2-methoxy phenol and cyclohexane yield was 1 h−1. The reaction mechanism showed that the Ru/ZSM-5 catalyst provoked the HDO compared to the others catalyst.

Performance of a Ni-Cu-Co/Al2O3 Catalyst on in-situ Hydrodeoxygenation of Bio-derived Phenol

The in-situ hydrodeoxygenation of bio-derived phenol is an attractive routine for upgrading bio-oils. Herein, an active trimetallic Ni-Cu-Co/Al2O3 catalyst was prepared and applied in the in-situ hydrodeoxygenation of bio-derived phenol. Comparison with the monometallic Ni/Al2O3 catalyst and the bimetallic Ni-Co/Al2O3 and Ni-Cu/Al2O3 catalysts, the Ni-Cu-Co/Al2O3 catalyst exhibited the highest catalytic activity because of the formation of Ni-Cu-Co alloy on the catalyst characterized by using X-ray powder diffraction (XRD), temperature programmed reduction (TPR), N2 physisorption, scanning electron microscope (SEM), and transmission electron microscope (TEM). The phenol conversion of 100% and the cyclohexane yield of 98.3% could be achieved in the in-situ hydrodeoxygenation of phenol at 240 °C and 4 MPa N2 for 6 h. The synergistic effects of Ni with Cu and Co of the trimetallic Ni-Cu-Co/Al2O3 catalyst played a significant role in the in-situ hydrodeoxygenation process of phenol, which not only had a positive effect on the production of hydrogen but also owned an excellent hydrogenolysis activity to accelerate the conversion of cyclohexanol to cyclohexane. Furthermore, the catalyst also exhibited excellent recyclability and good potential for the upgrading of bio-oils.

Revealing the factors determining the selectivity of guaiacol HDO reaction pathways using ZrP-supported Co and Ni catalysts

Guaiacol, a primary chemical derived from lignin, is still an attractive candidate as a cyclical carbon source in the petroleum industry. This work newly introduced Co/ZrP and Ni/ZrP catalysts and examined their activity for guaiacol hydrodeoxygenation (HDO) in a batch reactor at 573 K and under 70 bar of H2. Their catalytic, surface and textural properties were investigated by XRD, N2 adsorption-desorption, H2-TPR, H2-TPD, NH3-TPD, HAADF-STEM and H2-chemisorption. In addition, the overall reaction pathways of guaiacol to cyclohexane on Co/ZrP and Ni/ZrP were proposed. Guaiacol was converted to cyclohexane through two different pathways via two major intermediates: phenol (demethoxylation, PHE route) and 2-methoxycyclohexanol (hydrogenation, 2-M route). Co/ZrP preferred the PHE-route, while Ni/ZrP dominantly favored the 2-M-route, which resulted in a high cyclohexane yield when using Co/ZrP (76%). In this study, an ‘intrinsic H2 supply’ was determined to be the main factor for selecting the reaction pathway. Co/ZrP, with a low intrinsic H2 supply capacity, promoted a less H2-consuming pathway (PHE route), and Ni/ZrP, with a high intrinsic H2 supply, favored the more H2-consuming 2-M route. Likewise, lowering the H2 pressure (from 70 to 40 bar) could promote the PHE route and increase cyclohexane production (80%). However, the opposite trend was observed when the reaction temperature was reduced from 573 K to 523 K. For both Co/ZrP and Ni/ZrP catalysts, the production of PHE significantly decreased, while the same yield of 2-M was almost maintained. Thus, the pathway preference of Co/ZrP was reversed to the 2-M-route. Guaiacol HDO pathway preference over Co/ZrP and Ni/ZrP catalysts was characterized and the reaction conditions were investigated in this study, which could provide a guideline for effective ways to produce desired chemicals from guaiacol using Co/ZrP and Ni/ZrP.