Catalytic Hydroconversion Research Articles

Catalytic hydroconversion of HTL micro-algal bio-oil into biofuel over NiWS/Al2O3

The demand for energy worldwide and the environmental concerns are increasing over the years, and microalgae is a potential raw material for third-generation fuel. In this work, the Chlorella sorokiniana microalga was converted by hydrothermal liquefaction (HTL) into a bio-oil using a batch reactor at 300 °C, under 10 MPa, for 30 min. Then, the bio-oil was upgraded using a batch reactor at three temperatures (350 °C, 375 °C, and 400 °C) under 10 MPa (H2) over NiW/Al2O3 sulfided catalyst. The bio-oil and upgraded fractions were characterized by elemental analysis, GPC-RID/DAD, 13CNMR, Sim-Dis, and GC×GC–MS/FID to identify the bio-oil molecular composition and follow its evolution. The lipids in the initial biomass, composed mainly of C16 and C18 chains/triglycerides, were converted into C16 and C18 fatty acids during the HTL reaction, corresponding to 41 % of bio-oil. Then, during the upgrading stage, these carboxylic acids were converted into C15 to C18 n-alkanes through two routes: hydrogenation or decarboxylation/decarbonylation, which was favored by temperature increase. >60 % of upgraded bio-oil eluted on the diesel range, as observed by Sim-Dis. The higher heating value (HHV) increased from 36 MJ/kg in the HTL bio-oil to 47 MJ/kg in the oil upgraded at 400 °C, and the average molar mass decreased from 333 to 203 g/mol. Oxygen and nitrogen compounds such as phenols, phytosterols, pyrroles, indoles, carbazoles, and amides were identified and quantified. Some insights about sulfur compounds are also given. The degree of deoxygenation, denitrogenation and desulfurization was higher than 90 % after the upgrading stage at 400 °C. Nevertheless, heterocyclic nitrogen compounds remained in the upgraded biooil. Therefore, catalytic hydrotreatment is confirmed as a relevant technology for upgrading HTL micro-algal bio-oil. However, catalyst performances can be improved to reduce less reactive nitrogen components.

Mesoporous zeolite Beta supported Ni nanoparticles for the catalytic hydroconversion of extraction portion from Jinjitan subbituminous coal to cycloalkanes

The catalytic hydroconversion (CHC) of heavy carbon organic species (HCOSs) to cycloalkanes represents an importantly used chemical industry process due to the wide applicability of the resulting products in energy and fine chemistry. Despite the existing conventional catalysts applied to the CHC of HCOSs, the development of highly active bifunctional Ni-based heterogeneous catalysts for this process is still a challenge. Therefore, we show that the modified deposition–precipitation of nickel (II) nitrate on hydrothermally synthesized mesoporous zeolite Beta (MZB) prepares a Ni/MZB catalyst with a through-crosslinking mesopore structure and uniformly disperse Ni nanoparticles (NPs) at rough MZB crystal surface. The 10%Ni/MZB (10% Ni loading), in the presence of exposing on amount of accessible Lewis acid sites (LASs) and attaching Ni NPs by chemical bonding from the silica matrix of MZB skeleton, exhibits excellent activity to promote the CHC of all kind of aromatic rings and heteroatom-containing species, including chain alkanes, arenes, oxygen-containing organic compounds (OCOCs), nitrogen-containing organic compounds (NCOCs), and sulfur-containing organic compounds (SCOCs), to produce cycloalkanes and hydroarenes under mild conditions. Interestingly, density functional theory (DFT) calculations indicate that the transfer of biatomic active hydrogen (H…H) and heterogenous H+ from 10%Ni/MZB plays important roles during the CHC of diphenoxybenzene (DPOB). After being recycled 4 times, 10%Ni/MZB is still maintains high activity for CHC of DPOB under mild conditions.

Catalytic hydroconversion processes for upcycling plastic waste to fuels and chemicals

This review provides an overview of catalytic hydroconversion processes including hydrocracking, hydrogenolysis and hydrodeoxygenation for upcycling of plastic wastes into fuels and valuable chemicals.

Catalytic hydroconversion of poplar lignin over a nitrogen-doped carbon material-supported nickel prepared by in situ co-pyrolysis

A nitrogen-doped carbon material-support nickel was prepared by two-step in situ co-pyrolysis of glucosamine hydrochloride, melamine (MA), and Ni(NO3)2·6H2O, and used for the catalytic hydroconversion (CHC) of poplar lignin (PL). Under 2 MPa of initial H2 pressure at 270 °C for 4 h, 91.7 wt% of soluble portion and 24.7 wt% of aromatic monomer yield were obtained from the CHC of PL over Ni10/NDCMD. The characterization results confirmed that adding MA resulted in a larger specific surface area, abundant mesoporous structure, and defect sites, facilitating the dispersion of Ni-Nx and promoting the diffusion and mass transfer of PL and its intermediates. In addition, pyridinic nitrogen provides abundant anchoring sites for nickel atoms to inhibit Ni-Nx accumulation and increase metal-support interactions. Therefore, Ni10/NDCMD with better texture and more Ni-Nx sites exhibited excellent catalytic activity and recycle stability for the CHC of PL.

Selective catalytic hydroconversion of a low-temperature coal tar-derived crude phenols to cyclohexanol over a nitrogen-doped Co-based catalyst

An extraction-catalytic hydroconversion (CHC)-column chromatography strategy was designed for the CHC of crude phenols to obtain cyclohexanol (CH) and enrich non-substituted condensed arenes (NSCAs) from a low-temperature coal tar (LTCT). Phenanthrene, fluoranthene, and pyrene were enriched with purities of 94.3%, 90.1%, and 96.1%, respectively, by extraction with petroleum ether and methanol and subsequent gradient elution using a medium pressure preparative liquid chromatograph (MPPLC) and high pressure preparative liquid chromatograph. Co supported on a nitrogen-doped carbon material (NDCM) was prepared by one-step pyrolysis of a cobalt-organic framework under N2 atmosphere and crude phenols (CPs) were extracted from the LTCT. CH with a purity of 98.7% was obtained by catalytically hydroconverting CPs over Co/NDCM and subsequent elution using the MPPLC. The mechanism for the CHC of CPs over Co/NDCM was examined using phenol as the LTCT-related model compound. As a result, phenol was completely converted and the CH selectivity reached 97.7% in n-hexane under initial hydrogen pressure of 3 MPa at 140 °C for 3 h. The characterization of Co/NDCM and the distribution of products from the CHC of phenol indicate that Co/NDCM can activate H2 to H···H and the H···H transfer plays a crucial role in hydrogenating aromatic rings.

Facile synthesis of multifunctional poly(ionic liquid)s as an advanced three-way catalyst for the efficient production of lignite-derived arenes

The precise synthesis of multifunctional poly(ionic liquid)s (MFPILs) featuring basic sites, mesoporous channels, and hydrophobicity continues to be a substantial challenge. Moreover, the directional conversion of lignite to monocyclic arenes (MCAs) is highly attractive but particularly challenging on account of its geometrical complexity and chemical inertness. The efficiency of lignite directional conversion to MCAs over solid bases is substantially decreased by the presence of water molecules leading to the deactivation and leaching of basic sites. Herein, the novel solid bases, i.e., MFPILs with dibasic sites, unique hydrophobicity, and abundant mesoporous channels, were successfully fabricated by a radical multicomponent cross-linked copolymerization for the first time. Even more excitedly, the resulting MFPILs were demonstrated to be very efficient for directional catalytic hydroconversion of extraction residue from Dahuangshan lignite (DLER) into MCAs with 32.3 wt% yield, which is by far the highest value reported for lignite-derived MCAs by solid bases under similar conditions. The synergistic catalysis, i.e., hydrophobic microenvironment, mesoporous confinement, and synergistic effect of dibasic sites, for active hydrogen transfer of DLER conversion into MCAs over MFPILs is confirmed by characterization methods. The work not merely sheds substantial light on developing the novel solid bases, but also exhibits a potentially powerful catalyzing strategy to synthesize MCAs.

Evaluation of kraft and hydrolysis lignin hydroconversion over unsupported NiMoS catalyst

Catalytic hydroconversion of Kraft and hydrolysis lignins was for the first time compared in a batch reactor over an unsupported NiMoS-SBA catalyst. We also report the effect of key reaction parameters on the yields and properties of the products. The results obtained at 20 wt% catalyst loading for hydrolysis lignin showed the highest monomer yield of 76.0 wt%, which consisted of 39 wt% aromatics with the lowest alkylphenolics yield of 10.1 wt%. Identical operating conditions, 400 °C, 80 bar, 5 h at 10 wt% catalyst loading, were used to compare both lignins and the highest monomer yield (64.3 wt%) was found for the hydrolysis lignin, consisting of 16.0 wt% alkylphenolics and 20.1 wt% aromatic compounds. These values are considerably higher than those for Kraft lignin with its 47.0 wt% monomer yield. We suggest that the reason for high yields of monomeric units from hydrolysis lignin is that it is more reactive due to its lower ash and sulfur contents and the chemical structural differences compared to the Kraft lignin. More precisely, the bio-oil from hydrolysis lignin contained higher yields of small molecules, sourced from ring-opening of cellulose in the hydrolysis lignin, which could stabilize the reactive oligomeric groups. These yields were two to seven times higher from kraft and hydrolysis lignin, respectively, compared to those obtained without catalyst. The results showed that the NiMoS-SBA catalyst is a promising catalyst for reductive depolymerization of lignin and in addition that the regenerated catalyst had good stability for multiple reaction cycles.

Catalytic hydroconversion of two lignin-related model compounds over Ni/CeO2

Ni/CeO2 with medium-strong acidity was prepared by in-situ carbon templating (ISCT) and reduction with H2. Oxydibenzene (ODB) and benzyloxybenzene (BOB) were used as lignin-related model compounds (LRMCs). Over Ni/CeO2, ODB was completely converted into cyclohexane (CHI) under initial hydrogen pressure (IHP) of 2 MPa at 160 °C for 2 h and complete conversion of BOB to CHI and methylcyclohexane (MCH) was achieved under IHP of 2 MPa at 120 °C for 1.5 h. H…H transfer to the benzene rings (BRs) in the LRMCs and phenol from BOB hydrocracking results in the BR hydrogenation, while H+ transfer to the oxygen atom in BOB, hydrogenated ODB, and BOB-derived cyclohexanol (CHII) leads to the >CH-O- bond cleavage and subsequent dehydration of the resulting protonated CHII (PCHII). In addition, Ni/CeO2 exhibits an excellent reusability.

Catalytic hydroconversion of an organic waster oil to cyclanes over Ni/SiO2

An organic waster oil (OWO) was ultrasonically extracted with isometric acetone/carbon disulfide mixed solvent at room temperature to obtain extractable portion (EP) with the yield of 99.1%. Ni/SiO2 was prepared by a deposition–precipitation method. EP consist of arenes (34.1%), oxygen-containing organic compounds (OCOCs, 62.4%), and nitrogen-containing aromatics (NCAs, 3.5%) determined with a gas chromatograph/mass spectrometer (GC/MS). It was subjected to catalytic hydroconversion (CHC) over Ni/SiO2 in n-hexane under initial hydrogen pressure (IHP) of 4 MPa at 220 °C for different periods of time to obtain catalytically hydroconverted EPs (CHCEPs). All the organic species detected in EP were completely converted into cyclanes in CHCEP6 and the heat value increased from 28.52 to 37.04 MJ kg−1 by the CHC. In Ni/SiO2, highly dispersed nickel nanoparticles and mesoporous support with suitable acid sites play significant roles in hydrogenating aromatic rings and removing heteroatoms, respectively. To understand the mechanism for the CHC of EP, the catalytic activity of Ni/SiO2 was investigated using 4-cumylphenol (CP) and 1,3,5-triphenylbenzene (TPB) as the OWO-related model compounds. As a result, CP and TPB were completely converted over Ni/SiO2 in n-hexane at 220 °C or 200 °C under 4 MPa of IHP for 2 h, proving that Ni/SiO2 exhibits favorable CHC reactivity under mild conditions. Moreover, Ni/SiO2 has excellent cyclability after 4 runs and can be recovered by reduction with H2 at 500 °C for 4 h.

Synergistic catalysis: A powerful new strategy for the production of lignin-derived aromatic monomers

Efficient and selective conversion of lignin into aromatic monomers (AMs) is extremely essential for the economic feasibility of biorefinery. Nevertheless, the high catalytic efficiency of solid acid catalysts (SACs) for lignin conversion into AMs is remarkably weakened by the present of water produced during the above reaction leading to the deactivation and leaching of acidic sites. More importantly, the directional preparation of SACs with well-defined mesopores, hydrophobicity, and Brønsted-Lewis acidic sites still remains a grand challenge for heterogeneous catalyst development. To overcome these limitations, a desired multifunctional poly(ionic liquid)s (MFPILs) with above-mentioned structural and chemical properties were successfully constructed by an innovative synergistic regulation-induced co-polymerization. Then, MFPILs exhibit more excellent catalytic performance than poly(ionic liquid)s containing Lewis acidic site, Brønsted acidic site, or hydrophilicity alone with 47.9% conversion of lignin and 24.6 wt% yield of AMs, which is the excellent yield reported for the catalytic hydroconversion of lignin using non-precious-metal catalysts. The high catalytic performance of MFPILs for the production of lignin-derived AMs are attributed to the synergistic co-catalysis of the hydrophobic micro-environment, Brønsted-Lewis acidic sites, and mesoporous confinement, which was further confirmed by water contact angle, H2 temperature programmed desorption, and adsorption experiment. Further, MFPILs featuring magnetic recovery properties can be recycled for at least 10 run times without a significant lower catalytic activity. The work not only sheds some light on fabricating the novel SACs, but also develops a powerful new strategy to produce lignin-derived AMs.

Recent Advances in the Catalytic Hydroconversion of 5-Hydroxymethylfurfural to Valuable Diols.

Biomass, a globally available resource, is a promising alternative feedstock for fossil fuels, especially considering the current energy crisis and pollution. Biomass-derived diols, such as 2,5-bis(hydroxymethyl)furan, 2,5-bis(hydroxymethyl)-tetrahydrofuran, and 1,6-hexanediol, are a significant class of monomers in the polyester industry. Therefore, the catalytic conversion of biomass to valuable diols has received extensive research attention in the field of biomass conversion and is a crucial factor in determining the development of the polyester industry. 5-Hydroxymethylfurfural (HMF) is an important biomass-derived compound with a C6-furanic framework. The hydroconversion of HMF into diols has the advantages of being simple to operate, inexpensive, environmentally friendly, safe, and reliable. Therefore, in the field of diol synthesis, this method is regarded as a promising approach with significant industrialization potential. This review summarizes recent advances in diol formation, discusses the roles of catalysts in the hydroconversion process, highlights the reaction mechanisms associated with the specificities of each active center, and provides an outlook on the challenges and opportunities associated with the research on biomass-derived diol synthesis.

Catalytic Hydroconversion of 5-HMF to Value-Added Chemicals: Insights into the Role of Catalyst Properties and Feedstock Purity.

5-hydroxymethylfurfural (HMF) is an important bio-derived platform molecule that is generally obtained from hexoses via acid-catalyzed dehydration. It can be effectively transformed into a variety of value-added derivatives, thus being an ideal candidate for fossil replacement. Both HMF oxidation and hydrogenation processes enable the synthesis of numerous chemicals, monomers for polymerization, and biofuel precursors. This Review summarizes the most recent advances in heterogeneous catalytic hydroconversion of HMF into valuable chemicals with strong focus on 2,5-bishydroxymethyl furan (BHMF), 2,5-bishydroxymethyltetrahydrofuran (BHMTHF), and 2,5-dimethyltetrahydrofuran (DMTHF). In addition, multifunctional catalytic systems that enable a tunable production of various HMF derived intermediates are discussed. Within this chemistry, the surprising impact of HMF purity on the catalytic performance, such as selectivity and activity, during its upgrading is highlighted. Lastly, the remaining challenges in the field of HMF hydroconversion to the mentioned chemicals are summarized and discussed, taking into account the knowledge gain of catalyst properties and feedstock purity.

Integrated catalytic hydroconversion of three crop stalks to valuable oxygenated organic chemicals

Two flexible regulation systems were designed and used for the integrated catalytic hydroconversion (CHC) of lignocellulose to valuable oxygenated organic chemicals. Under the dual constraints of initial H2 pressure (IHP) and temperature, three crop stalks can be almost completely degraded over a hydrothermally stable Ru/La(OH)3 in one-pot, while the synergetic transfer of active hydrogen effectively promotes the cleavage of >C-O- bridged bonds in organic matter with highly complex structures during this period. As a result, abundant >Cal-O- (>32%) and >C=O (>24%) derived platform chemicals such as alkanols, cyclanols, carboxylic acids, and esters were obtained at high IHP and low temperature. Correspondingly, various >Car-O- (>50%) and >C=O (>30%) derived platform chemicals such as phenols, alkoxy-substituted phenols, ketones, and carboxylic acids dominated the derived bio-oils at low IHP and high temperature. The designed selective CHC strategies have the characteristics of convergent conversion to the two major derivative chemical demand directions. Therefore, these two atom-economic and effective degradation approaches are conducive to obtaining abundant functional small molecules, which can be further converted to various downstream platform products.

Compositional Features of the Light Fraction from One/Two‐Step Effective Cascade Catalytic Hydroconversion of the Extraction Residue from Naomaohu Lignite

AbstractNaomaohu lignite (NL) was extracted with isometric acetone/carbon disulfide mixed solvent under ultrasonic irradiation. The extraction residue (ER) was subjected to non‐catalytic hydroconversion (NCHC) and one/two‐step cascade catalytic hydroconversion (CHC) in n‐hexane at 300 °C under 4 MPa of H2 over magnetic solid superacid (MSSA) and superbase (MSSB). The NCHC‐soluble portion from the NCHC (SPNCHC) and CHC‐soluble portion from the one/two‐step cascade CHC (SPA, SPB, SPA‐B, and SPB‐A) were analyzed with a gas chromatograph/ mass spectrometer (GC/MS). The results show that the yields of SPA and SPB are 18.65 % and 16.31 %, respectively, which are much higher than that of SPNCHC (1.26 %). According to the analysis with GC/MS, SPA and SPB are rich in phenol, dimethylnaphthalene, cresol, trimethylphenols, and xylenols, while alkanes are the predominant group component in the SPNCHC, indicating that MSSA selectively catalyzed the cleavage of Car−Calk and Calk−O bridged bonds, whereas MSSB tended to cleave Car−O and Calk−O bridged bonds connecting some aromatic rings in the ER. The yield of SPB‐A was as high as 11.07 % and SPA‐B was only 0.59 %. The results showed that more soluble species in the ER could be further released through the cascade CHC procedures. Benzyloxybenzene was used as a coal‐related model compound to probe the possible mechanisms of one/two‐step cascade CHC of the ER.

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.

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.

Nitrogen-doped porous carbon supported nickel nanoparticles as catalyst for catalytic hydroconversion of high-temperature coal tar

A novel and highly active nitrogen-doped porous carbon-supported nickel catalyst Ni@N-PC was successfully developed by a thermolysis of nickel-based zeolitic imidazolate frameworks growing on both sides of graphitic carbon nitride and used for catalyzing hydroconversion of isopropanol soluble portion from ultrasonic extraction of high-temperature coal tar (ISPHTCT). The active nickel nanoparticles were mainly encapsulated on the top of carbon nanotubes and partially dispersed on the surface of carbon nanosheets. Naphthalen-1-ol was used as a model compound to investigate the catalytic hydroconversion activity under different reaction conditions and reveal the mechanism for catalytic hydroconversion. The ISPHTCT and catalytic hydroconversion products of ISPHTCT (ISPCHCP) were analyzed with gas chromatograph/mass spectrometer. The results show that 70% of naphthalen-1-ol was converted at 160°C and completely converted at 200°C for 120 min, and the ISPHTCT was greatly upgraded. A total of 180 organic compounds including 33 nitrogen-containing organic compounds, 11 sulfur-containing organic compounds and 39 oxygenates were identified in ISPHTCT, while no obvious nitrogen-containing organic compounds, sulfur-containing organic compounds and oxygenates were detected in ISPCHCP, indicating the excellent performance of Ni@N-PC for heteroatom removal. All the alkenes, cyclenes and alkynes were saturated and the majority of arenes were converted to cyclanes by catalytic hydroconversion over Ni@N-PC, which exhibited high catalytic hydrogenation activity.

Catalytic ethanolysis of Dahuangshan lignite and directional upgrading of two derived soluble mixtures

An in-situ and ex-situ cascade upgrade strategy was designed and used for upgrading Dahuangshan lignite-derived soluble mixtures (LDSMs) to obtain value-added chemicals and clean liquid fuels (CLFs), respectively. In the H2-free catalytic ethanolysis, Ni/mordenite can effectively activate ethanol and promote the transfer of various free radicals including H·, CH3CH2·, and CH3CH2O·, which synchronously facilitates the cleavage of bridged bonds in Dahuangshan lignite and the in-situ removal of heteroatoms (HAs) from LDSMs. As a result, the total yield of LDSMs increased from 40.6 to 66.5 wt%, wherein that of ethanol-soluble portion (ESP) increased from 21.4 to 32.4 wt%. Interestingly, alkanes and arenes with higher relative content (RC, 38.1%) were detected in ESPC (for catalytic ethanolysis), while arenols (24.7%) dominate ESPN (for ethanolysis). The analysis with a quadrupole exactive orbitrap mass spectrometer further confirmed the significant decrease in the relative abundance of HAs, especially Ox class species, in ESPC. In addition, ESPN and ESPC with different properties were further used for enriching derived chemicals and for obtaining CLFs by catalytic hydroconversion (CHC), respectively. After the CHC, the total RCs of alkanes and cyclanes in the soluble portion (SP) are as high as 71.3%, and the content of HA-containing organic compounds was further decreased. Therefore, such SP containing less HAs is an attractive CLF precursor. A ternary mixed solvent was also designed for rapidly separating the SP from ESPN. The total RC of alkanes and arenes in PE5 as well as arenols in M5 are as high as 79.4 and 70.9%, respectively. Molecular dynamics simulations were further used to reveal the rapid enrichment mechanisms with ternary mixed solvents.

Solvent Effect on the Hydroconversion of Lignin-Related Model Compounds over MoO3

Benzyloxybenzene (BOB) and oxybis(methylene)dibenzene (OBMDB) were used as lignin-related model compounds (LRMCs). Three protic solvents (PSs), i.e., methanol, ethanol (E), and isopropanol, and two aprotic solvents (ASs), i.e., ethyl acetate and n-hexane, were selected to evaluate their effects on the catalytic hydroconversion (CHC) of the LRMCs over MoO3. Under the same conditions, the PSs are more effective for the CHC of LRMCs than the ASs. Under the optimal conditions in E, both BOB and OBMDB are completely converted and the total product yields are 200 and 198.1 mol %, respectively. MoO3 undergoes the surface modification, such as carburization and oxygen vacancy (OV) formation, during the reaction, which is crucial for the CHC of the LRMCs. The OV formation is determined by the self-transformation degree of PSs and the dispersity of ASs to MoO3 through the analyses of solvent-related environmental variables. In addition, solvents affect the CHC of LRMCs by controlling the adsorption performance of MoO3.

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.