Coal-related Model Compounds Research Articles

An acidic ionic liquid modified microfiber attapulgite-supported nickel for catalytic hydroconversion of α,ω-diarylalkanes

An acidic ionic liquid modified microfiber attapulgite (MFA)-supported nickel was prepared by thermally decomposing nickel tetracarbonyl onto MFA modified with an acidic ion liquid (AIL, 1-sulfobutyl-3-methylimidazolium trifluoromethanesulfonate). It was characterized with multiple instruments and used for catalyzing hydroconversion of coal-related model compounds (CRMCs) di(1-naphthyl)methane, diphenylmethane, bibenzyl, and 1,3-diphenylpropane. The results indicate that Ni/MFA@AIL effectively catalyzes hydroconversion of the CRMCs to afford cyclanes and alkylcyclanes by inducing the formation of H+, H−, and biatomic active hydrogen species.

Effect of Pretreatment with Sulfuric Acid on Catalytic Hydrocracking of Fe/AC Catalysts

Activated carbon (AC) was modified by H2SO4 and used as a support for catalyst. The Fe2S3/AC-T catalyst was prepared by deposition-precipitation method and used to catalyze hydrocracking of coal-related model compound, di(1-naphthyl)methane (DNM). The properties of catalyst were studied by N2 adsorption-desorption, X-ray diffraction, and scanning electron microscopy. The result showed that ferric sulfate and acidic centers had synergetic effect on hydrocracking of DNM when using Fe2S3/AC-T as catalyst, the optimal loading of Fe is 9 wt.%. Hydroconversion of the extraction residue from Guizhou bituminous coal was also studied using Fe2S3/AC-T as the catalyst. The reaction was conducted in cyclohexane under 0.8 Mpa of initial hydrogen pressure at 310°C. The reaction mixture was extracted with petroleum ether and analyzed by GC/MS. Amounts of organic compounds which fall into the categories of homologues of benzene and naphthalene were detected. It suggested that the catalyst could effectively catalyze the cleavage of C-C-bridged bonds.

Complete hydrocracking of dibenzyl ether over a solid acid under mild conditions

A novel solid acid was prepared by impregnating trifluoromethanesulfonic acid (TFMSA) onto mesoporous ZrO2 coated attapulgite (MPZCA) via one-pot synthesis method. Dibenzyl ether (DBE) was used as a coal-related model compound to evaluate the catalytic activity of TFMSA/MPZCA for cleaving Calk–O bridged bonds in low-rank coals. The results show that DBE conversion over TFMSA/MPZCA could reach 100% at 160°C in C2H5OH without charging H2. TFMSA/MPZCA proved to be stable after 4 cycles with only slight loss in catalytic activity. Moreover, a H+ transfer mechanism was proposed, which reasonably deduces possible pathways for DBE hydrocracking over TFMSA/MPZCA.

Applications of metals and metal sulphides in catalytic hydrocracking of coal and their related model compounds

Coal liquefaction is a promising approach to reduce pollution comparing to combustion. Industrialisation of indirect coal liquefaction (ICL) has succeeded by Sasol in South Africa. In ICL process, coal is treated as resource of carbon and hydrogen rather than aromatic compounds. Nevertheless, the percent of chemicals in the products of Sasol reaches up to /3. Chemicals oriented direct coal liquefaction (DCL) is superior to ICL considering energy efficiency and structural characteristics of coal, especially when the target products are aromatic compounds. The key to achieve it is highly active and selective catalysts for DCL. Herein, metal catalysts employed in DCL and coal-related model compounds are viewed. The existing problems and road maps of metal catalysts for DCL are pointed out. Bi- or multi-metal catalysts on specific supporter with high activity and selectivity are candidate catalysts for DCL. Besides, reaction mechanisms are also discussed. [Received: July 10, 2014; Accepted: January 14, 2015]

A highly active solid acid for specifically catalyzing di(1-naphthyl)methane hydrocracking in cyclohexane

A highly active solid acid was prepared by impregnating trifluoromethanesulfonic acid (TFMSA) onto mesostructured zirconium oxide (MSZO). Di(1-naphthyl)methane (DNM) was used as a coal-related model compound to evaluate the catalytic activity of TFMSA/MSZO for cleaving strong C–C bridged bonds in coals. As a result, TFMSA/MSZO was found to be effective for hydrocracking DNM to naphthalene and 1-methylnaphthalene in cyclohexane without adding gaseous hydrogen and MSZO is a much better support than activated carbon, γ-Al2O3, and ZSM-5 zeolite. Based on the kinetic investigation, the apparent activation energy of DNM hydrocracking over TFMSA/MSZO is only 32.0kJ·mol−1, which is much lower than the dissociation energy (355.6kJ·mol−1) of the bridged bond in DNM. The proton transfer directly from TFMSA/MSZO and/or via cyclohexane dehydrogenation over TFMSA/MSZO to the ipso-position of DNM could be the crucial step for DNM hydrocracking.

Multifunctional and highly active Ni/microfiber attapulgite for catalytic hydroconversion of model compounds and coal tars

A highly dispersive nickel catalyst supported on microfiber attapulgite (MFA) was prepared. Benzene, naphthalene, triphenylmethane, 9-phenylanthracene, 1-methoxynaphthalene (MON), benzyloxybenzene, and oxybis(methylene)dibenzene were used as coal-related model compounds (CRMCs) to evaluate the catalytic activity. A conventional Ni/MFA (Ni/MFA–C) was prepared by an impregnation method. Ni/MFA is significantly active for catalytic hydroconversion of the CRMCs than Ni/MFA–C. Ni/MFA-catalyzed hydroconversions of industrial low-temperature coal tar (LTCT) and high-temperature coal tar (HTCT) were also investigated. The results show that the Car–O bond in MON was specifically cleaved over Ni/MFA followed by catalytic hydrogenation of the resulting naphthalene to afford tetralin. Both unsaturated hydrocarbons and heteroatom-containing organic compounds in the LTCT and HTCT were completely hydroconverted to alkanes over Ni/MFA under optimum conditions, indicating that Ni/MFA catalyzes both hydrocracking and hydrogenation. According to multiple analyses, nickel nanoparticles were formed on the surface of MFA in Ni/MFA.

Pyrolysis behaviors of two coal-related model compounds on a fixed-bed reactor

The bibenzyl (BB) and benzyloxybenzene (BOB) were selected as coal-related model compounds, and their pyrolysis behaviors between 500°C and 700°C were investigated on a fixed-bed reactor. The pyrolysis products were analyzed by gas chromatography–mass spectrometer (GC–MS) and gas chromatography (GC), and the bond dissociation energy (BDE) was calculated with density functional theory (DFT) methods at B3LYP/6-31G (d) level. The results showed that the conversion in pyrolysis of BOB was higher than that of BB. The pyrolysis product distributions and BDE calculation indicate that Caliphatic–Caliphatic bond dissociation is the primary step for BB pyrolysis, while Caliphatic–O bond dissociation is the primary step for BOB pyrolysis. The differences in pyrolysis behaviors between BB and BOB indicate that the existence of oxygen atom will reduce the BDE thus being preferentially dissociated under pyrolysis. The initial radicals should be stabilized by some more reactive radicals, which lead to higher liquid yield.

Analysis of some coal-related model compounds and coal derivates with atmospheric solids analysis probe mass spectrometer

A series of coal-related model compounds (CRMCs) were analyzed with an atmospheric solids analysis probe/time of flight-mass spectrometer (ASAP/TOF-MS). Pyrene, anthracene, and phenanthrene were ionized to generate stable radical molecular cation (M+•) and protonated molecular cation ([M+H]+). The ratio of [M+H]+ to M+• is positively related to the superdelocalizability of the condensed arenes (CAs), indicating that the CA ionizations rely on the intrinsic reactivities of the CA to a certain extent. Fragmental ions were formed via cleavage and/or rearrangement of [M+H]+/M+• from bridged bond-containing CRMCs during ASAP/TOF-MS analysis. Their formation is related to drying gas temperature and the stabilities of fragmental species. Using ASAP/TOF-MS, a reaction mixture from di(1-naphthyl)methane hydrocracking was directly and rapidly analyzed, and as coal derivates succinic acid and polymethyl benzenepolycarboxylates were identified in the water-soluble portions from a coal and char oxidation within short time, respectively. The fact suggests that ASAP/TOF-MS could be used for real-time monitoring organic mixtures during the reactions of CRMCs and coal conversion.

Evaluation of atmospheric solids analysis probe mass spectrometry for the analysis of coal-related model compounds

An atmospheric pressure solids analysis probe (ASAP) was mounted on a commercial atmospheric pressure chemical ionization source with simple modifications. A series of coal-related model compounds (CRMCs) were analyzed using a time-of-flight mass spectrometry equipped with the ASAP ion source. The ionization mechanism and fragmentation pathways for CRMCs were investigated. The temperature of desolvation gas played a crucial role to the response signal, especially for the association behavior of CRMCs. With a fixed desolvation gas temperature, radical cation (M+) or protonated molecule ([M+H]+) was the predominant ion generated by corona discharge of ASAP depending on the temperature of drying gas. Fragment ions were produced from bridged bond breaking of the precursor ions, rearrangement reactions and loss of neutral fragments such as H2O, CH2O, CO, CH3OH and CO2. The fragmentation pathways can offer a better understanding of fundamental mechanism of chemical bond breaking for coal derivatives and further explore the application of coal directional conversion.

A new solid acid for specifically cleaving the Car[sbnd]Calk bond in di(1-naphthyl)methane

Three catalysts were prepared by impregnating the same volume of pentachloroantimony (PCA), trimethylsilyl trifluoromethanesulfonate (TMSTFMS), or isometric PCA and TMSTFMA into an activated carbon (AC). Di(1-naphthyl)methane (DNM) was used as a coal-related model compound to evaluate their catalytic activity. The results show that CarCalk bond in DNM can be specifically cleaved over each catalyst to afford naphthalene and 1-methylnaphthalene under pressurized hydrogen at temperatures up to 300°C, but as a new solid acid (NSA), PCA–TMSTFMS/AC is significantly more active for DNM hydrocracking than the other two catalysts. FTIR and SEM analyses reveal the strong interactions among PCA, TMSTFMS, and the AC in the NSA. NH3-TPD analysis suggests that the NSA should exhibit appreciably stronger acidity than the other two catalysts. The strong interactions may result in the appreciably stronger acidity of the NSA than that of the other two catalysts and thereby facilitate DNM hydrocracking. It is presumed that H2 was heterolytically cleaved to immobile H− and mobile H+. The addition of mobile H+ to ipso-position of DNM should be crucial step for DNM hydrocracking.

The Microwave-assisted Hydrogenation of 9,10-Diphenylanthracene over Pd/C

Palladium/activated carbon (Pd/C) catalyzed hydrogenation of 9,10-diphenylanthracene (DPA), used as a coal-related model compound, was investigated under microwave irradiation. The effects of reaction temperature, pressure, and time on DPA yield were studied. The results show that DPA hydrogenation proceeds at much lower temperatures and hydrogen pressure under microwave irradiation than those by conventional heating and Pd/C mainly promote ipso hydrogenation of DPA. The related mechanism was discussed.

Catalysis of [formula omitted]/ZrO 2 in the reactions of coal-related model compounds

In this paper, diphenylmethane, bibenzyl, phenetole and diphenyl ether were used as coal-related model compounds (CRMCs) to study the catalysis of SO 4 2 - /ZrO 2 in the process of coal liquefaction. Based on the reaction kinetics of CRMCs in tetralin and identification of reaction products, the catalytic mechanisms of SO 4 2 - /ZrO 2 for CRMCs were discussed. The results indicate that the CRMCs were mainly hydrocracked by SO 4 2 - /ZrO 2. The conversion of tetralin solvent increased with the reactivity of CRMC. Reactions of tetralin mainly included hydrocracking, isomerization, alkylation and hydrogenation/dehydrogenation. A cationic reaction mechanism was proposed, which can successfully interpret the reaction of CRMCs and tetralin catalyzed by SO 4 2 - /ZrO 2.

REACTIONS OF METHOXY-SUBSTITUTED AROMATIC COAL MOOELS IN SUPERCRITICAL SOLVENTS

Abstract Reactions of α- and β-methoxy naphthalene and anisole in supercritical benzene and toluene were studied at 420 °C and 3.9-4.4 MPa pressure. The decomposition of these lower rank coal related model compounds in both solvents was found to obey the first order rate law. While naphthols were present in the reaction mixture of methoxy naphthalenes, phenol and cresoles were present in that of anisole. In addition to these products, diphenyl or dibenzyl was also present in the reaction mixture of supercritical benzene or toluene, respectively. The reactions between models and solvents might be explained by free radical and intermolecular rearrangement reaction pathways.

Solvent effect on coal liquefaction

Effectiveness of various hydrogen-donor solvents toward coal liquefaction has been investigated by carrying out hydrogenation or hydrogenolysis of coal-related model compounds such as benzophenone, trans-stilbene, anthracene, and 9-benzylphenanthrene. The hydrogen-donatability of the hydroaromatic hydrocarbon is governed by the lability of the benzylic CH bond. 9,10-Dihydroanthracene and 9,10-dihydrophenanthrene are good hydrogen-donors not only in hydrogenation of unsaturated structures but also in deoxygenation of benzophenone. Hydrogen-donatabilities of polar solvents highly depend on the structure of the hydrogen acceptor. The rates for reduction of polar compounds are considered to be governed by the relative rate of the initiation step where ionic interaction between solvent and hydrogen-acceptor is important. Superior hydrogen-donatabilities of 5,6,7,8-tetrahydro-2-naphthol and 1,2,3,4-tetrahydroquinoline are ascribed to their ambident character as hydroaromatic and phenol or secondary amine.

Reassessment of zeolite and molecular sieve framework infrared vibrations

The phenyl ethyl ether (PEE) and benzyloxybenzene (BOB) were selected as coal-related model compounds, and their catalytic pyrolysis behaviors in the presence of Ni-modified HZSM-5 zeolite were studied in a fixed-bed reactor. Nickel was introduced on HZSM-5 zeolite by wet impregnation. The catalysts were characterized by XRD, FT-IR, H2-TPR and NH3-TPD, and the effect of hydrogen reduction pretreatment on the catalytic performance was studied. NiO/HZSM-5 can significantly improve the yield of phenols in the liquid phase products of the two model compounds. Compared with Ni/HZSM-5, NiO/HZSM-5 exhibits superior pyrolysis conversion of PEE.

Zinc chloride catalyzed decomposition of 1,2-dihydronaphthalene at 165.degree.C. A coal-related model compound study

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTZinc chloride catalyzed decomposition of 1,2-dihydronaphthalene at 165.degree.C. A coal-related model compound studyRobert R. Beishline, Brian Gould, Edward B. Walker, Douglas K. Stuart, Joanna Schultzski, John K. Shigley, Kelly Calvert, Don K. Dalling, and Larry L. AndersonCite this: J. Org. Chem. 1982, 47, 9, 1668–1673Publication Date (Print):April 1, 1982Publication History Published online1 May 2002Published inissue 1 April 1982https://doi.org/10.1021/jo00348a011RIGHTS & PERMISSIONSArticle Views62Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (763 KB) Get e-Alerts Get e-Alerts

Hydrogenolysis of coal-related model compounds by carbon monoxide-water mixture

Model organic compounds have been subject to hydrogenolysis reactions using CO and H 2O under industrial conditions as used for lignite and residual oil. Twenty-eight compounds, including diphenylmethane, indane, tetralin, anthracene, diphenyl ether, indene, benzophenone and xanthene were used. The purpose is to study the hydrogenolysis behaviour of compounds with structures as found in coal and residual oil. Using a Co-Mo catalyst, scission of the CC chain connecting two aromatic rings is enhanced by increased chain length of the molecule. Ether bonds are broken more easily than CC bonds. With the exception of decalin, cyclic CC bonds are more resistant to cleavage than linear bonds. Alcohol hydroxyl, and carbonyl groups of stilbene are the easiest to reduce but phenolic hydroxyl groups are stable. The Co-Mo catalyst promoted hydrolysis of ether bonds as well as hydrogenolysis. The method of the study is considered to be more effective for hydrogenolysis of organic compounds than the reported use of alkali and tetralin because of milder reaction conditions which are required.