MPa Initial Hydrogen Pressure Research Articles

Stable and selective multi-porous nickel nanoparticles catalysts for hydrocracking of dibenzyl ether supported by DFT studies

Preparation of clean fuel from biomass has a crucial significance on the development and utilization of renewable clean energy. In this study, a multi-stage porous mordenite supported nickel nanoparticles catalyst (Nix%/HMOR) was prepared, which showed that its acid content, acidity, porosity, specific surface area and metal dispersion were significantly improved while the crystallization strength was basically the same compared with microporous mordenite. In order to study the conversion mechanism of biomass energy, dibenzyl ether was selected as a typical lignin model compound. Under the condition of Ni10%/HMOR in n-hexane at 160 °C for 2 h under 5 MPa of initial hydrogen pressure, the conversion of dibenzyl ether was 100 % and the selectivity of methyl cyclohexane was 84.4 %, which manifested that Ni10%/HMOR had good activity in the selective hydrocracking process under mild conditions. Furthermore, density functional theory (DFT) was selected to study the activation energies of different reaction sites on dibenzyl ether bridge bonds and the recombination process of free radicals in the reaction process. It comes to a conclusion that the O atom on the C-O bridge bond is easier to be attacked by H*, and the C-O bond of the unsaturated aromatic ring is easier to break. During the recombination of free radicals, the two C-O bond breaking energy barriers of OMD are different, and H free radicals are more likely to attack the O atom in cyclohexane-methanol. It is conducive to the formation of stable compound 1 - (cyclohexylmethyl) − 1-methylcyclohexane and its isomers.

Catalytic hydroconversion of a cotton stalk-derived soluble portion over Ni/sepiolite

Catalytic hydroconversion (CHC) of a lignin-derived soluble portion to value-added chemicals is of great significance. Ni/sepiolite was successfully prepared via a impregnation method and used for the CHC of a cotton stalk-derived soluble portion (CSDSP). Cyclanes and cyclohexanols are the main products with total relative content of 64.7% from the CHC of CSDSP over Ni/sepiolite. To better understand the reaction mechanism, the CHC of oxydibenzene (ODB), benzyloxybenzene (BOB), and guaiacol over Ni/sepiolite were investigated. They were completely converted at 240 °C under 4 MPa of initial hydrogen pressure. According to the resulting products, H…H and H+ are the main active hydrogen species in the CHC and H+ transfer induces the cleavage of -CH2-O- bond in BOB followed by hydrogenating benzene ring (BR), while the CHC of ODB and guaiacol proceeds via the hydrogenation of BR and subsequent cleavage of -CH2-O- bond.

Investigation on the catalytic performance of magnetic copper ferrite nanoparticles in the catalytic hydroconversion of Hanglaiwan long flame coal

Magnetic copper ferrite (CuFe2O4) was prepared by hydrothermal synthesis method and used for the catalytic hydroconversion (CHC) of Hanglaiwan long flame coal (HLFC) in cyclohexane under 1 MPa of initial hydrogen pressure (IHP) at 300 °C for 4 h. The total yield of soluble portion (SP) from the CHC is 33.7 wt%, significantly being higher than that (10.5 wt%) from the non-CHC (NCHC) under the same conditions. The main compounds detected in SPCHC (for CHC) are arenes and oxygen-containing organic compounds (OCOCs). Benzyloxybenzene (BOB), 2-(benzyloxy)naphthalene (BON), oxybis(methylene)dibenzene (OBMDB), oxydibenzene (ODB), and 2,2′-oxydinaphthalene (ODN) were used as HLFC-related model compounds to investigate the catalytic activity of CuFe2O4 and understand the CHC mechanism of HLFC. According to the model reactions, CuFe2O4 activates H2 to biatomic active hydrogen (H…H) and splits H…H to mobile H+ and immobile H-. H+ addition to oxygen atoms (OAs) in >C-O- bridged bonds (BBs) cleaves the BBs and releases SP during the CHC of HLFC.

Synergistic effect of acidity and active phases for nickel nanoparticles supported HZSM-5 catalysts on lignin-related model compounds hydrodeoxygenation performance under mild conditions

The cleavage >C-O- bridge bonds and saturate aromatic rings of oxygen compounds from lignin is increasingly important in catalytic hydrodeoxygenation (HDO) for lignin upgrading and value-added utilization. Therefore, the catalytic behavior of a series of HZSM-5 (HZ-5) with different Si/Al ratios (n = 25, 50, 170, and 200) and acidity levels supported Ni nanoparticles (NPs) were prepared by modified deposition-precipitation method for catalytic HDO of lignin-related model compounds (LRMCs). The effects Ni loading, HZ-5 texture, and acid properties on catalytic activity, products distribution, and mechanism were systematically investigated. Furthermore, as-prepared catalysts were characterized by X-ray diffraction, N2 adsorption, scanning electron microscope, energy dispersive spectrometer, pyridine infrared, NH3-temperature programmed desorption, X-ray photoelectron spectrometer, and used for catalytic HDO of LRMCs with different >C-O- bridge bonds and aromatic rings, including oxydibenzene, oxybis(methylene)dibenzene, benzyloxybenzen, and oxydinaphthalene. These results indicate that Ni/HZ-5(n) can activate H2 to biatomic hydrogen (H‧‧‧H) and heterogeneously split H‧‧‧H to relatively mobile H+ and immobile H- with synergistic effect of Ni NPs, further leads to cleave the >Cal-O- and >Car-O- bridge bonds with different conversion through active hydrogen transfer. Additionally, effective modulate of catalytic HDO of LRMCs would be helpful to further maximize the target product yield on the basis of this mechanism at 160 °C for 5 MPa initial hydrogen pressure (mild conditions).

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.

Selective catalytic hydroconversion of organic waster oil to cyclanes over a coal fly ash-derived zeolite-supported nickel catalyst: Waster to energy

An organic waster oil (OWO) from petroleum processing was extracted with petroleum ether (PE) to PE-extractable portion (PEEP) and extraction residue 1 (ER1), which was extracted with isometric acetone/carbon disulfide mixed solvent (MS) to MS-extractable portion (MSEP) and extraction residue 2 (ER2). A zeolite topology molecular sieve (ZTMS) was prepared from coal fly ash. Ni/ZTMS was prepared by loading Ni into ZTMS. Both PEEP and MSEP were subjected to catalytic hydroconversion (CHC) over Ni/ZTMS in n-hexane under 4 MPa of initial hydrogen pressure (IHP) at 240 °C for 2 h. The results show that most of arenes, hydroarenes, and oxygen-containing organic compounds (OCOCs) and all the nitrogen-containing aromatics (NCAs) in PEEP and all the arenes and NCAs together with most of OCOCs in MSEP were converted to cyclanes. To understand the mechanism for the CHC of PEEP and MSPE from the OWO, 2-phenylphenol (PP) was used as the OWO-related model compound. As a result, PP was completely converted and the yield of target product bicyclohexane (BCH) reached to 97.7% over Ni/ZTMS in n-hexane under 4 MPa of IHP at 240 °C for 2 h. The characterizations of Ni/ZTMS and time profiles of the products from the CHC of PP reveal that Ni/ZTMS can activate H2 to H⋯H and heterolytically cleave H2 to relatively mobile H+ and immobile H-; H⋯H addition to benzene ring in PP causes PP hydrogenation, while H+ addition to the oxygen in the resulting 2-phenylcyclohexanol (PCH) and 2-cyclohexylcyclohexanol (2-CHCH) induces the dehydroxylation of PCH and CHCH.

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.

Catalytic hydroconversion of the light residue from Yinggemajianfeng lignite over a solid superacid

TFMSA/ATA was prepared by impregnating trifluoromethanesulfonic acid (TFMSA) onto the acid-treated attapulgite (ATA). Yinggemajianfeng lignite was extracted ultrasonically with a mixed solvent obtain the extract and extraction residue (ER), and then ER was separated by density difference to obtain the light residue (LR). The non-catalytic hydroconversion (NCHC) and TFMSA/ATA-catalyzed hydroconversion of LR were investigated in cyclohexane at 160 °C under 4 MPa of initial hydrogen pressure for 12 h. The soluble portions from NCHC (SPNCHC) and catalytic hydroconversion (SPCHC) were analyzed with a Fourier transform infrared spectrometer and gas chromatograph/mass spectrometer. As a result, the yield of SPCHC (60.0%) is significantly higher than that of SPNCHC (1.8%), suggesting that the thermal dissolution of LR at 160 °C is negligible and TFMSA/ATA significantly catalyzed the hydrocracking of LR to release SPCHC. Oxygen-containing organic compounds, especially 4-methylpent-3-en-2-one and 4-hydroxy-4-methylpentan-2-one, are predominant produced from the CHC of LR, suggesting that the cleavage of > Cα-Oβ- and > Cβ-Oα- bonds in LR significantly proceeded during the CHC of LR over TFMSA/ATA. Such a mechanism was proved by the CHC of oxybis(methylene)dibenzene.

Deep hydroconversion of ethanol-soluble portion from the ethanolysis of Hecaogou subbituminous coal to ultra-clean liquid fuel over hierarchical porous zeolite Y supported Ni–Co nanoparticles

A hierarchical porous zeolite Y (HPZY) supported Ni–Co catalyst was prepared by pyrolyzing nickel tetracarbonyl and using modified deposition-precipitation to highly disperse Ni–Co nanoparticles onto HPZY. Hecaogou subbituminous coal was effectively ethanolyzed to obtain ethanol-soluble portion (ESPE) in a high yield (21.2%). Sequentially, ESPE was subjected to the deep hydroconversion (DHC) over prepared Ni10%-Co3%/HPZY at 150 °C under 4 MPa of initial hydrogen pressure for 24 h in n-heptane to produce deeply hydroconverted ethanol-soluble portion (ESPDHC). All the group components in ESPE, including arenes (53.3%), oxygen-containing organic compounds (24.4%), and nitrogen-containing aromatics (2.3%) were completely converted to chain alkanes (CAs, 36.8%), cyclanes (39.2%), and hydroarenes (24.0%). In addition, the hydroisomerization of CAs and hydroreforming of aromatic rings (ARs) in ESPDHC are predominant over Ni10%-Co3%/HPZY with more accessibility of active sites under mild conditions. Ni10%-Co3%/HPZY with suitable acidity and highly dispersed Ni–Co nanoparticles can effectively activate H2 to H⋯H and further heterogeneously split H⋯H to H+ and H−. H⋯H and H+ transfer plays crucial roles in the DHC of ESPE. Correspondingly, the related mechanisms are evidenced by the DHC of 2,2′-oxydinaphthalene (ODN) over Ni–Co/HPZY. Ni10%-Co3%/HPZY maintains high activity for the DHC of ODN under mild conditions after 4 recycles.

Hydrotreatment of fast pyrolysis liquid over Cr and P-modified catalysts with high Ni content

Hydrotreatment of birch wood pyrolysis liquid (PL) was carried out at 350 °C and 6.0 MPa initial hydrogen pressure (RT) for 4 h in a batch autoclave using promising high-loading Ni-based catalysts stabilized by SiO2. Different additives (Cu, Mo, Cr, P) were used to modify the catalysts. The products in liquid organic (OPh) and aqueous phases (AqPh) after PL hydrotreatment were characterized by different methods, such as gas chromatography-mass spectrometry (GC–MS), Fourier-transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), etc. Herein, the performance of the catalysts was evaluated by considering the yield and chemical composition of the products (gaseous phase, OPhs, AqPhs, and coke). For the MoCr-containing system, a higher yield of the aqueous phase with low O/C ratio was observed that could be explained by more effective hydrodeoxygenation of water-soluble compounds due to Ni-Mo-Cr solid solutions and coordinatively unsaturated Cry+ and Mox+ sites. P-modified NiCuMoP-SiO2 and NiCrP-SiO2 catalysts reveal more intense CO2 formation very likely due to decarboxylation over Ni3P particles, thus leading to the decrease in the oxygen content in organic phase to 14 wt.%. Fresh reduced catalysts were examined by CO chemisorption, X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM) to provide insights into the structure and morphology. High resistance to coke formation was evidenced according to CHNS analysis of spent samples, besides, the stability of catalysts was additionally assessed by X-ray diffraction.

Deep catalytic hydroconversion of straw-derived bio-oil to alkanes over mesoporous zeolite Y supported nickel nanoparticles

A supported nickle catalyst was prepared by loading ca. 11% of nickel nanoparticles (NNPs) on mesoporous zeolite Y (MZY) and denoted as Ni11%/MZY. A straw was methanolyzed at 300 °C to obtain methanol-soluble portion as a straw-derived bio-oil (SDBO) in the yield of 19.3%. According to the analysis with a gas chromatograph/mass spectrometer, SDBO consists of arenes (7.8%), oxygen-containing organic compounds (82.8%), nitrogen-containing organic compounds (6.3%), and sulfur-containing organic compounds (3.1%). It was subjected to catalytic hydroconversion (CHC) over Ni11%/MZY in n-hexane under 5 MPa of initial hydrogen pressure (IHP) at 160 °C for 16 h. As a result, all the compounds in SDBO were converted to chain alkanes (60.1%) and cyclanes (39.9%). In Ni11%/MZY, uniformly dispersed NNPs and strong Lewis acid sites in the defective crystal texture of MYZ play crucial roles in hydrogenating aromatic rings and removing heteroatoms (HAs), respectively. Benzyloxybenzene (BOB) was used as a lignin-related model compound. The main product from the CHC of BOB over Ni11%/MZY in n-hexane under 5 MPa of IHP at 160 °C for 2 h is methylcyclohexane in the yield of 90.9%, indicating that both hydrogenation of benzene rings and deoxygenation significantly proceeded. After being recycled 4 times, Ni11%/MZY is still active for the CHC of BOB.

Green and effective catalytic hydroconversion of an extractable portion from an oil sludge to clean jet and diesel fuels over a mesoporous Y zeolite-supported nickel catalyst

A mesoporous Y zeolite (MPYZ)-supported nickel catalyst (Ni/MPYZ with 10% of Ni loading) was prepared by modifying deposition-precipitation (MDP) to uniformly disperse Ni nanoparticles (NNPs) onto MPYZ. An oil sludge (OS) was exhaustively extracted with isometric carbon disulfide and acetone mixed solvent to obtained the extractable portion (EPOS) in the yield of 90.6%. EPOS was subjected to the catalytic hydroconversion (CHC) over Ni10%/MPYZ at 160 °C under 5 MPa of initial hydrogen pressure (IHP) for 18 h in n-hexane to afford catalytically hydroconverted EP (EPCHC). The results show that alkenes, aromatics, and heteroatom-containing compounds (HACCs, some of which are also aromatics) in EPOS were completely converted to chain alkanes and cyclanes. Ni/MPYZ can effectively activate H2 to biatomic active hydrogen (H⋯H) and heterogeneously split H2 to relatively mobile H+ and immobile H− attached on the surface of Ni/MPYZ. The transfer of H⋯H and H+ to EPOS plays crucial roles in the CHC of EPOS. Such mechanisms are evidenced by the CHC of benzyloxybenzene over Ni/MPYZ. Ni10%/MPYZ maintained high activity for the CHC after 5 repeated cycles.

Catalytic Hydroconversion of Runbei Lignite over a Highly Active Solid Superacid

AbstractA highly active solid superacid, denoted as TFMSA/CNOFW, was prepared by calcining Ni‐organic framework (NOFW) to get calcined NOFW (CNOFW), into which trifluoromethanesulfonic acid (TFMSA) was impregnated. It was used to catalyze the hydroconversions of both oxybis(methylene)dibenzene (OBMDB) and the extraction residue (ERRL) from Runbei lignite (RL). The results show that over TFMSA/CNOFW, OBMDB was hydrocracked to toluene as the main product, indicating that TFMSA/CNOFW can heterolytically spit H2 to relatively mobile H+ and immobile H− attached on TFMSA/CNOFW. The addition of H+ to the oxygen atom (OA) in OBMDB produces phenylmethylium (PMI) and phenylmethanol (PMII). Toluene was yielded by the following 2 reactions: (1) the abstraction of H− by PMI from the TFMSA/CNOFW surface and (2) H+ addition to the OA in PMII, subsequent dehydration to form PMI, and the abstraction of H− by PMI from the TFMSA/CNOFW surface. In the similar mechanism, ERRL was hydrocracked to acetone‐soluble portion in the yield of 78.6% over TFMSA/CNOFW under 4 MPa of initial hydrogen pressure at 310 °C for 4 h.

Bifunctional metallic-acidic mechanisms of hydrodeoxygenation of eugenol as lignin model compound over supported Cu, Ni, Pd, Pt, Rh and Ru catalyst materials

The hydrodeoxygenation (HDO) reaction kinetics of lignin monomer model compound eugenol was systematically investigated over various commercially available catalysts typically used for lignin valorisation by hydrotreatment. The role of noble metals Pt, Pd, Rh, Ru, and non-noble Ni and Cu on C was investigated in the previous studies, while the present work is focused on the support (Al2O3, SiO2, SiO2-Al2O3, TiO2, HZSM-5) effect on the catalyst activity and selectivity, being estimated experimentally (at 225, 275, 325 °C and 5 MPa of initial hydrogen pressure) and in silico. The micro-kineticmodel took into consideration mass transfer resistances through convective films (gas bubbles and catalyst particles), reaction kinetics in bulk liquid, adsorption/desorption and surface reaction kinetics on metallic and acidic active sites, considering the occurrence of all reactions on both types of sites. The contribution of each support was quantitatively evaluated in terms of adsorption, desorption, and reaction rate constants and activation energies. SiO2-Al2O3 and HZSM-5 showed superior contribution to the activity of the methoxyl and hydroxyl group removal from oxygenated aromatics and particularly saturated species. Except for the above-mentioned materials Caromatic–O hydrogenolysis activity was not substantially affected, while the acidity of the support notably promoted Caliphatic–O cleavage. Contribution to overall hydrogenation rate was practically negligible in presence of acidic sites. It has been also noted that the contribution of supports was not very prominent when very active noble metal phases were used (such as Ru), while it came to the fore in the case of almost inactive Cu, being responsible for formation of 4-propylphenol at 325 °C. Based on microkinetic modelling results, Sankey diagrams were formulated for the first time to represent pathway flux and graphically demonstrate the contribution of each catalytic reaction participating in the overall eugenol HDO mechanism over the used catalysts (and corresponding intermediates) within a complex reaction network, as well as the engagement of metallic and acidic sites.

Catalytic hydroconversion of soluble portion in the extraction from Hecaogou subbituminous coal to clean liquid fuel over a Y/ZSM-5 composite zeolite-supported nickel catalyst

A novel and highly active Y/ZSM-5 composite zeolite (YZCZ)-supported nickel bifunctional catalyst (Ni/YZCZ) was prepared using a modified deposition–precipitation method to uniformly disperse Ni nanoparticles (NNPs) onto YZCZ. Hecaogou subbituminous coal was exhaustively extracted with isometric carbon disulfide and acetone mixed solvent under ultrasonic irradiation to afford the extractable portion (EP) in the yield of 18.4%. EP was subjected to catalytic hydroconversion (CHC) in n-hexane over Ni/YZCZ under 5 MPa of initial hydrogen pressure at 160 °C for 24 h to afford catalytically hydroconverted EP (CHCEP). Both EP and CHCEP were analyzed with a gas chromatograph/mass spectrometer (GC/MS) and quadrupole exactive orbitrap mass spectrometer (QPEOTMS). As a result, cyclanes, alkenes, and hydroarenes were only detected in CHCEP and the relative content (RC) of alkanes in CHCEP is much higher than that in EP, while the RCs of both arenes, especially condensed arenes, and oxygen-containing organic compounds in EP are predominantly higher than those in CHCEP and nitrogen-containing organic compounds were only detected in EP. According to the CHC of coal-related model compound oxydibenzene (ODB), Ni/YZCZ can effectively activate H2 to biatomic active hydrogen (H⋯H), which is then split to an immobile H− attached on Ni/YZCZ and a relatively mobile H+. The H⋯H transfer leads to the hydrogenation of aromatic rings (ARs) in EP and ODB followed by heteroatom removal from the hydrogenated EP and ODB. In addition, due to the appropriate acidity, uniformly dispersed NNPs, and mesoporous structure of YZCZ, Ni/YZCZ proved to be still active for the CHC after 3 cycles and recoverable.

Directional Catalytic Hydroconversion of Oxybis (methylene)dibenzene and an Extract from Piliqing Subbituminous Coal over a Magnetic Difunctional Solid Superbase

AbstractAn active and novel magnetic difunctional solid superbase catalyst Ni‐Mg2Si/attapulgite powder (AP) was prepared by thermally decomposing nickel tetracarbonyl onto the as‐synthesized Mg2Si/AP followed by impregnating Mg2Si onto AP in CCl4 and characterized by multiple analyses. It was also successfully used in the catalytic hydroconversion (CHC) of coal‐related model compound oxybis (methylene) dibenzene (OBMDB) and an extract (E) from Piliqing subbituminous coal (PSBC) in n‐hexane. As a result, OBMDB was completely converted to methylcyclohexane by the CHC under 3 MPa of initial hydrogen pressure at 240 °C for 2 h. Ni‐Mg2Si/AP can activate H2 to biatomic active hydrogen (H…H) and split H2 to immobile H+ attached on the Ni‐Mg2Si/AP surface and relatively mobile H−. Then the bridged linkage (BL) in OBMDB can be cleaved by H− attack on a α‐carbon atom in OBMDB, producing toluene and benzyloxy anion, which abstracts H+ from the Ni‐Mg2Si/AP surface to afford phenylmethanol (PM). The α‐carbon in PM is attacked by H‐ to generate toluene and HO−. H…H transfers to benzene ring in toluene yields methylcyclohexane. The soluble portion (SP) from the CHC (SPE‐CHC) and non‐CHC (NCHC) (SPE‐NCHC) of E were analyzed with a gas chromatograph/mass spectrometer and Fourier transform infrared spectrometer. Non‐substituted cycloalkanes (NSCAs) are predominant in the SPE‐CHC, accounting for 66.9 % of the total group components, and interestingly 65.3 % of NSCAs is cyclohexane, while non‐substituted arenes are the most abundant in the SPE‐NCHC. The results indicate that the CHC is beneficial to the fracture of COCBB and hydrogenation of ARs to produce more NSCAs.

Systems and methods for cracking hydrocarbon streams such as crude oils utilizing catalysts which include zeolite mixtures

A novel and highly active Y/ZSM-5 composite zeolite (YZCZ)-supported nickel bifunctional catalyst (Ni/YZCZ) was prepared using a modified deposition–precipitation method to uniformly disperse Ni nanoparticles (NNPs) onto YZCZ. Hecaogou subbituminous coal was exhaustively extracted with isometric carbon disulfide and acetone mixed solvent under ultrasonic irradiation to afford the extractable portion (EP) in the yield of 18.4%. EP was subjected to catalytic hydroconversion (CHC) in n-hexane over Ni/YZCZ under 5 MPa of initial hydrogen pressure at 160 °C for 24 h to afford catalytically hydroconverted EP (CHCEP). Both EP and CHCEP were analyzed with a gas chromatograph/mass spectrometer (GC/MS) and quadrupole exactive orbitrap mass spectrometer (QPEOTMS). As a result, cyclanes, alkenes, and hydroarenes were only detected in CHCEP and the relative content (RC) of alkanes in CHCEP is much higher than that in EP, while the RCs of both arenes, especially condensed arenes, and oxygen-containing organic compounds in EP are predominantly higher than those in CHCEP and nitrogen-containing organic compounds were only detected in EP. According to the CHC of coal-related model compound oxydibenzene (ODB), Ni/YZCZ can effectively activate H2 to biatomic active hydrogen (H⋯H), which is then split to an immobile H− attached on Ni/YZCZ and a relatively mobile H+. The H⋯H transfer leads to the hydrogenation of aromatic rings (ARs) in EP and ODB followed by heteroatom removal from the hydrogenated EP and ODB. In addition, due to the appropriate acidity, uniformly dispersed NNPs, and mesoporous structure of YZCZ, Ni/YZCZ proved to be still active for the CHC after 3 cycles and recoverable.

Enhanced hydrogenation of aromatic rings and hydrocracking of >Car[sbnd]O[sbnd] bridged bonds in the extraction residue from Piliqing subbituminous coal over a magnetic difunctional solid superbase

Ni-Mg2Si/attapulgite powder (AP) was prepared by thermally decomposing nickel tetracarbonyl onto the as-synthesized Mg2Si/AP by impregnating Mg2Si onto AP in CCl4. Its catalytic performance was evaluated by the catalytic hydroconversion (CHC) of oxydibenzene (ODB) in n-hexane under different reaction conditions. Both ODB conversion and cyclohexane selectivity are 100 % by the CHC of ODB over Ni-Mg2Si/AP under 3 MPa of initial hydrogen pressure at 240 °C for 4 h. However, almost no ODB was converted without Ni-Mg2Si/AP under the same conditions. The results show that Ni-Mg2Si/AP could activate H2 to biatomic active hydrogen (H⋯H) and H−, resulting in the hydrogenation of aromatic rings (ARs) and the hydrocracking of >CarO bridged bonds (COBBs), respectively. Additionally, the catalyst was also successfully applied in the CHC of extraction residue (ER) from Piliqing subbituminous coal (PSBC) in n-hexane. The group components of the soluble portion (SP) from CHC and non-CHC (NCHC) (SPCHC and SPNCHC) of ER were analyzed with a gas chromatograph/mass spectrometer. The yield (36.4 %) of SPCHC is significantly higher than that (1.8 %) of SPNCHC. More alkyl-substituted arenols (ASAs), anisoles, and methoxy-substitued cresols exist in SPNCHC, while SPCHC contains more normal alkanes (NAs), non-substituted cycloalkanes, alkylcyclohexanes, tetralins, and octahydroanthracenes. NAs are predominant in SPCHC, while ASAs are the most abundant in SPNCHC, indicating that the CHC facilitates the hydrocracking COBBs and hydrogenating ARs. ODB conversion is as high as 91.2 % after recycling 4 times. Therefore, the catalyst might be potential to produce coal-derived chemicals and clean liquid fuels to facilitate coal efficient conversions owing to its high activity, difunctionality, stability, and good recyclability.

Studying the Effect of the Process Temperature on the Degree of Bio-Oil Hydrotreatment at Low Hydrogen Contents over NiCu–SiO2 Catalyst with a High Metal Loading

The hydrotreatment of pyrolysis bio-oil by hydrodeoxygenation at 6.0 MPa initial hydrogen pressure in the temperature range of 150–350°C and the presence of a NiCu–SiO2 catalyst synthesized using the sol-gel method is studied. The stability of the catalyst including the agglomeration of active component particles and the deposition of carbon on its surface is also investigated. It is shown that the content of oxygen in the products of the hydrotreatment of lignocellulose pyrolysis liquid decreases from 37 to 15 wt % upon an increase in the process temperature. Using a CHNS-O-analyzer, it is established that the amount of coke on the catalyst’s surfaces at a temperature of 350°C decreases by 4 times, compared with that formed at 150°C. X-ray diffraction shows that increasing the process temperature results in the gradual agglomeration of particles with a subsequent reduction in their size at high temperatures due to the dissolution of active catalyst components in the reaction medium.

Catalytic Hydrogenation of Levulinic Acid into Gamma-Valerolactone Over Ni/HZSM-5 Catalysts

A series of Ni/HZSM-5 catalysts with different Ni-loadings and Si/Al ratios were prepared by incipient wetness impregnation and employed for catalytic hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL). Their physicochemical properties were characterized by X-ray diffraction, nitrogen adsorption–desorption, X-ray photoelectron spectrometer, temperature-programmed desorption of ammonia,transmission electron microscopy, temperature-programmed reduction of hydrogen, and pyridine-adsorbed infrared spectroscopy. The diffraction peaks assigned to Ni phase were not observed, implying that nickel particles were small and had a high dispersion on the supports. The catalysts with a strong acidity and the appropriate ratio of Bronsted (B) acid sites to Lewis (L) acid sites (B/L = 4.9) show an excellent activity and selectivity for the hydrogenation of LA to GVL. High conversion of LA and selectivity towards GVL were achieved over 5 wt% Ni/HZSM-5-50. The maximum GVL yield of 100% over 5 wt% Ni/HZSM-5-50 was obtained under the optimized reaction conditions of 210 °C, 2 h, and 3 MPa initial hydrogen pressure.