Non-catalytic Hydroconversion Research Articles

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.

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.

Highly selective catalytic hydrocracking >CH-O- bridged bonds in an alkali lignin over Ni/Hβ

An active bifunctional nickel-based catalyst was prepared by decomposing Ni(CO)4 to dispersive metallic Ni on Hβ zeolite and successfully applied in the catalytic hydroconversion (CHC) of an alkali lignin (AL). Detailed elemental composition, functional groups, and molecular compositions of the soluble portions (SPs) from non-catalytic hydroconversion (SPNCHC) and CHC (SPCHC) were characterized with an elemental analyzer, a Fourier transform infrared spectrometer, and a gas chromatograph/mass spectrometer (GC/MS). As a result, alkoxalkanes, phenol, cresol, veratrols, alkyl-substituted 1,4-dimethoxyphenols, 2,5-dimethylfuran, 3-hydroxyneopentanal, 4-methylpent-3-en-2-one, 4-methoxy-4-methylpentan-2-one, 1-(2,4-dihydroxy-3-tolyl)propan-1-one, and 2,5-dimethylhex-4-enoic acid only appear in SPCHC, and yields of multiple alkyl-substituted phenols, p-alkylanisoles, diols, non-substituted and alkyl-substituted methoxyphenols, and substituted phenylethanones in SPCHC are significantly higher than those in SPNCHC. The mechanism for catalytically hydrocracking >CH-O- bridged bonds over Ni/Hβ is proposed using benzyloxybenzene (BOB) and phenethoxybenzene as AL-related model compounds. Ni/Hβ proved to be stable after 3 cycles with relatively small loss in catalytic activity for catalyzing the hydrocracking of >CH-O- bonds in BOB.

Catalytic hydroconversion of extraction residues from two Chinese lignites to arenes

A solid superacid TFMSA/MPZCA was prepared by impregnating trifluoromethanesulfonic acid (TFMSA) into mesoporous zirconia-coated attapulgite (MPZCA). Using TFMSA/MPZCA, the catalytic hydrocracking of coal-related model compounds (CRMCs) oxybis(methylene)dibenzene (OBMDB), benzyloxybenzene (BOB), and di(1-naphthyl)methane (DNM) and the catalytic hydroconversion (CHC) of extraction residues (ERs, isometric carbon disulfide/acetone-insoluble portion) from Huozhou lignite (HL) and Shaerhu lignite (SL) in cyclohexane without H2 were investigated. According to the model reactions, H+ released from TFMSA in TFMSA/MPZCA plays a crucial role in cleaving the > Calk-O- and > Car-C < bridged linkages (BLs) in the CRMCs, and the BLs of > Calk-O- in OBMDB and BOB can be completely cleaved at 170 °C and 190 °C for 3 h, respectively, while the BL of > Car-C < in DNM was not completely cleaved even at 320 °C. At 300 °C, the yields of soluble portions (SPs) from the CHC of HL- and SL-derived ERs significantly increase compared with the non-catalytic hydroconversion of both ERs. Arenes are predominantly abundant in the SPs from the CHC of both ERs and the most abundant compound in the SPs is mesitylene.

Catalytic hydroconversion of derivates from Naomaohu lignite over an active and recyclable bimetallic catalyst

Fe/attapulgite powder (AP), Ni/AP, and Fe-Ni/AP were prepared by thermally decomposing iron pentacarbonyl (IPC), nickel tetracarbonyl (NTC), and different molar ratios of IPC to NTC onto AP in ethoxyethane, respectively. Their activities for the catalytic hydrocracking of di(1-naphthyl)methane (DNM) were compared under the same conditions. As a result, the activity of Fe-Ni-S/AP (Fe:Ni = 2:1) for DNM hydrocracking is significantly higher than that of other catalysts used. DNM conversion is near 100% over Fe-Ni-S/AP with Fe:Ni = 2:1. Over the catalyst, H2 can be effectively split to H, which attacks the ipso-position of DNM to cleave the Car-Calk bridged bond in DNM. Naomaohu lignite was subjected to thermal dissolution/ethanolysis in ethanol to afford soluble portion 1 (SP1, yield 56.0%) and residue 1 (R1) followed by non-catalytic hydroconversion (NCHC) and catalytic hydroconversion (CHC) of SP1 and R1 at 300 °C using Fe-Ni-S/AP with Fe:Ni = 2:1 as the catalyst to afford SPNCHC, SPCHC, SP2 (yield 2.3%), and SPII (yield 11.2%). According to gas chromatography/mass spectrometric analysis, arenes are the most abundant in SPCHC, accounting for 21.9%, while the most abundant group component in SPNCHC are non‑nitrogen ketones, accounting for 20.0%.

Catalytic hydroconversion of Yinggemajianfeng lignite over difunctional Ni-Mg2Si/γ-Al2O3

A highly active difunctional Ni-Mg2Si/γ-Al2O3 was prepared by thermally decomposing nickel tetracarbonyl onto γ-Al2O3 impregnated with Mg2Si. The non-catalytic hydroconversion (NCHC) and catalytic hydroconversion (CHC) of the extract (E) and extraction residue (ER) from Yinggemajianfeng lignite were investigated over Ni-Mg2Si/γ-Al2O3 at 240 °C in n-hexane. Benzyloxybenzene and oxybis(methylene)dibenzene were used as lignite-related model compounds to speculate the possible mechanisms for the catalytic hydrocracking and hydrogenation over Ni-Mg2Si/γ-Al2O3. As a result, more organic matter in ER was converted to soluble portion (SP) by the CHC than by the NCHC. The main SP from the CHC are chain alkanes and cyclanes, while that from the NCHC is rich in arenes and oxygen-containing organic compounds. The results indicate that Ni-Mg2Si/γ-Al2O3 effectively catalyze the hydrocracking of >Calk–O– linkages and the hydrogenation of aromatic rings in E and ER.

Catalytic hydroconversion of Yiwu lignite over solid superacid and solid superbase

Trifluoromethanesulfonic acid supported on attapulgite powder (TFMSA/AP) and Mg2Si/γ-Al2O3 were facilely prepared by impregnating TFMSA onto AP and Mg2Si onto γ-Al2O3. The extraction residue from Yiwu lignite (YLER) was subjected to non-catalytic hydroconversion (NCHC) and catalytic hydroconversion (CHC) over TFMSA/AP and Mg2Si/γ-Al2O3, respectively. Detailed molecular compositions of the soluble portions from the NCHC (SPNCHC) and CHC over TFMSA/AP (SPCHC-A) and Mg2Si/γ-Al2O3 (SPCHC-B) were characterized with a gas chromatograph/mass spectrometer. As a result, the yields of SPCHC-A and SPCHC-B are 19.6% and 17.5%, respectively, which are much higher than that of SPNCHC (1.04%), suggesting that both TFMSA/AP and Mg2Si/γ-Al2O3 show excellent activity for the CHC of YLER. Arenes and arenols are predominant in SPCHC-A and SPCHC-B, respectively, while large amounts of alkanoates were detected in SPNCHC. The results indicate that TFMSA/AP effectively catalyzes the cleavage of Car–Calk and Calk–O bridged bonds (BBs) in YLER, while Mg2Si/γ-Al2O3 significantly promotes the cleavage of C–O BBs in YLER. Di(1-naphthyl)methane, 1-methylnaphthalene, oxydibenzene, and benzyloxybenzene were used as coal-related model compounds (CRMCs) for the CHC to further explore the catalysis of TFMSA/AP and Mg2Si/γ-Al2O3. The results show that TFMSA/AP not only releases mobile H+ but also heterolytically splits H2 to form an immobile H− and a mobile H+, leading to the cleavage of Calk–Car and Calk–O BBs in the CRMCs. In contrast, Mg2Si/γ-Al2O3 facilitates heterolytically splitting H2 to an immobile H+ and a mobile H−, resulting in the cleavage of C–O BBs in the CRMCs.

Catalytic hydroconversion of the extraction residue from Naomaohu lignite over an active and separable magnetic solid superbase

A highly active magnetic solid superbase (MSSB) was prepared by impregnating Mg2Si onto γ-Al2O3-coated ferroferric oxide nanoparticles via one-pot synthesis method and successfully applied in the catalytic hydroconversion (CHC) of the extraction residue (ER) from Naomaohu lignite. Large amounts of chain alkanes and arenes were detected in the soluble portion (SP) from the non-catalytic hydroconversion of the ER, while oxygen-containing organic compounds are predominant in the SP from the CHC of the ER, indicating that MSSB catalyzes the cleavage of CO bridged bonds in the ER. Oxybis(methylene)dibenzene was used as the lignite-related model compound to evaluate the catalytic activity of MSSB. The results show that MSSB facilitates heterolytically splitting H2 to release H− and subsequent H− transfer, leading to the cleavage of CO bridged bonds.

A recyclable and highly active magnetic solid superbase for hydrocracking C[sbnd]O bridged bonds in sawdust

A novel and highly active magnetic solid superbase (MSSB) with extraordinary recovery and recycling properties was prepared by impregnating Mg2Si onto mesoporous silica coated magnetite via one-pot preparation and successfully applied in the catalytic hydroconversion (CHC) of sawdust at 220°C. Detailed molecular compositions of the soluble portions from non-catalytic hydroconversion (SPNCHC) and CHC (SPCHC) were characterized with a Fourier transform infrared spectrometer and gas chromatograph/mass spectrometer (GC/MS). As a result, the yield of SPCHC is significantly higher than that of SPNCHC and most of the GC/MS-detectable compounds in SPCHC are guaiacols, while SPNCHC is rich in guaiacols and esters, indicating that MSSB effectively catalyzed the cleavage of CO bridged bonds in sawdust. The mechanism for catalytically hydrocracking CO bridged bonds over MSSB is proposed using benzyloxybenzene and oxybis(methylene)dibenzene as model compounds. MSSB can be easily separated by using an external magnetic field and the recovered MSSB proved to be still highly active for catalyzing the hydrocracking of CO bridged bonds in sawdust.

Effects of hydrogen and FeNi–S/γ-Al2O3 on the hydroconversion of extraction residue from Geting bituminous coal in cyclohexane

Extraction residue from Geting bituminous coal (ERGBC) via ultrasonic extraction with isometric carbon disulfide/acetone binary solvent was subjected to thermal dissolution (TD), thermal dissolution under pressurized nitrogen (TDN), non-catalytic hydroconversion (NCHC), and catalytic hydroconversion (CHC) in cyclohexane at 300°C for 3h. The catalyst was prepared by thermally decomposing Fe(CO)5 and Ni(CO)4 onto γ-Al2O3. The reaction mixtures from TD, TDN, NCHC, and CHC were sequentially extracted with petroleum ether, carbon disulfide, methanol, acetone, and isometric acetone/carbon disulfide binary solvent to afford extracts 1–5 (E1–E5). Detailed characterizations of the extracts were performed with a gas chromatography/mass spectrometer (GC/MS) and Fourier transform infrared spectrometer. The results show that the yields of E1 and E3 from CHC are appreciably higher than those from others, suggesting the great influence of CHC on the breakage of -CH2- and -O- linkages connected to condensed aromatic rings. According to analysis with GC/MS, alkanes and arenes are the most abundant species in each E1, in which most of the arenes are methylarenes. Arenols and phthalates are the predominant oxygen-containing organic compounds. Arenes with 1 or 2 ring(s) markedly increase by using H2, especially in the presence of the catalyst. The H. catalytically generated over FeNi–S/γ-Al2O3 and the stabilizing effect of H2 on the generated radicals could play crucial roles in cleaving bridged linkages connected to condensed aromatic rings and thereby enhance the yields of alkylarenes through NCHC and CHC. Related mechanisms for the formation of some species derived from NCHC and CHC of ERGBC are discussed.

Catalytic hydroconversion of Geting bituminous coal over FeNi–S/γ-Al2O3

FeNi/γ-Al2O3 was prepared by thermally decomposing iron pentacarbonyl and nickel tetracarbonyl onto γ-Al2O3. Geting bituminous coal (GBC) was subjected to noncatalytic hydroconversion (NCHC) and catalytic hydroconversion (CHC) in the presence of FeNi/γ-Al2O3 and sulfur at 300°C for 3h. The reaction mixtures from both NCHC and CHC were fractionated to extracts 1–5 (E1–E5) by sequential extraction. The molecular compositions of E1–E5 were characterized with a Fourier transform infrared spectrometer, gas chromatography/mass spectrometer (GC/MS), and atmospheric solid analysis probe/time of flight-mass spectrometer (ASAP/TOF-MS). The results show that the yields of E1–E5 from CHC of GBC are obviously higher than those from NCHC. According to GC/MS analysis, the group components in E1 from the CHC are dominated by alkanes, arenes, and arenols in remarkable higher yields than those from NCHC, and most of the arenes and arenols are alkyl-substituted ones. The addition of active hydrogen atoms catalytically generated over FeNi–S/γ-Al2O3 to the ipso-position of condensed aromatic rings (CARs) in GBC could play a crucial role in cleaving–CH2− and–O− linkages connected to the CARs and thereby enhanced the yields of alkylarenes and alkylarenols through CHC. Meanwhile, the partial hydrogenation of some CARs during CHC could promote the radical hydrogen transfer along with thermal rupture of some relatively strong bonds to produce soluble molecules. According to ASAP/TOF-MS analysis, the soluble species from both NCHC and CHC have molecular mass distributions ranging from 100 to 500 u. A series of polar and/or involatile organic species.

Light fraction from catalytic hydroconversion of two Chinese coals in cyclohexane over a solid acid

Two Chinese coals, Shengli lignite and Shenmu–Fugu subbituminous coal, were subjected to non-catalytic hydroconversion (NCHC) and catalytic hydroconversion (CHC) in cyclohexane at 300°C for 3h under pressurized hydrogen using a solid acid as the catalyst, which was prepared by impregnating isometric pentachloroantimony and trimethylsilyl trifluoromethanesulfonate into an activated carbon. The reaction mixtures from both NCHC and CHC were sequentially extracted with petroleum ether, carbon disulfide, methanol, acetone, and isometric acetone/carbon disulfide mixed solvent to afford extracts 1–5 (E1–E5). The results show that both E1 and total extract yields from CHC are appreciably higher than those from NCHC of each coal. E1 from either NCHC or CHC of each coal was analyzed with a gas chromatograph/mass spectrometer (GC/MS) and an atmospheric solids analysis probe/time of flight mass spectrometer (ASAP/TOF-MS). GC/MS analysis shows that each E1 consists of alkanes, arenes, and oxygen-containing organic compounds (OCOCs), and most of the arenes are methyl-substituted ones, whereas alkenyl groups only appear on benzene ring; most of the OCOCs are arenols, especially alkylarenols. According to ASAP/TOF-MS analysis, organic compounds with molecular masses ranging from 500 to 950u appear in E1 from CHC of both coals.

Catalytic hydroconversion of extraction residue from Shengli lignite over Fe–S/ZSM-5

A highly dispersive Fe/ZSM-5 as the precursor of Fe–S/ZSM-5 was prepared by decomposing Fe(CO)5 onto ZSM-5 zeolite at 250°C. Shengli lignite (SL) was isolated to extractable portion (EP) and extraction residue (ER) by exhaustive extraction with isometric carbon disulfide/acetone mixed solvent (IMCDSAMS) under ultrasonic irradiation. The EP and ER were analyzed with a direct analysis in real time ionization source coupled to ion trap mass spectrometer. Both of them and SL were analyzed with a Fourier transform infrared spectrometer. The ER was subjected to non-catalytic hydroconversion (NCHC) and catalytic hydroconversion (CHC) over Fe–S/ZSM-5, which was formed by in situ reaction of Fe/ZSM-5 with sulfur added, in cyclohexane under pressurized hydrogen at 300°C. The reaction mixtures were sequentially extracted with petroleum ether, carbon disulfide, methanol, acetone, and IMCDSAMS to afford extracts 1–5 (E1–E5), which were analyzed with a gas chromatography/mass spectrometer (GC/MS). As model reactions, the CHCs of di(1-naphthyl)methane (DNM) and diphenylmethane (DPM) over Fe–S/ZSM-5 were also conducted in cyclohexane at 300°C. The results show that more than 50% of organic matter in the ER was converted to a soluble portion by the CHC, whereas the yield of soluble portion from the NCHC is only 10.52%. GC/MS-detectable species only appear in the E1, which mainly consists of alkanes, arenes, and arenols either from the NCHC or from the CHC. DNM was selectively hydrocracked to naphthalene and 1-methylnaphthalene over Fe–S/ZSM-5, while DPM hydrocracking did not proceed, indicating that Fe–S/ZSM-5 catalyzed the formation of radical hydrogen from molecular hydrogen and subsequent radical hydrogen transfer (RHT) to the ipso-position of naphthalene ring in DNM. Some CH2 and O in the ER could be connected to condensed aromatic rings (CARs). Analogously, RHT to the ipso-position of CARs in the ER resulted in the release of arenes and phenols from the ER.

Catalytic hydroconversion of Lingwu bituminous coal over Fe-S/γ-Al&lt;SUB align="right"&gt;2O&lt;SUB align="right"&gt;3

Fe-S/γ-Al2O3 was prepared by thermally decomposing Fe(CO)5 onto γ-Al2O3 and subsequent sulphurisation with sublimed sulphur in a magnetically stirred autoclave and used as the catalyst for catalytic hydroconversion (CHC) of Lingwu bituminous coal (LBC). Non-catalytic hydroconversion (NCHC) and CHC of LBC were conducted in cyclohexane under 5 MPa of initial hydrogen pressure at 300°C. The reaction mixtures were extracted with petroleum ether and analysed with a gas chromatography/mass spectrometer. The results show that Fe-S/γ-Al2O3 significantly catalysed the formation of hydroarenes, arenes and arenols and completely removed 2,5-dimethylthiophene from LBC.

The Amorphous Alloy-catalyzed Hydroconversion of Demineralized Shengli Coal Liquefaction Residue Under Microwave Irradiation

Microwave-assisted hydroconversion of demineralized Shengli lignite liquefaction residue (DMSLLR) over Ni-B/SiO2 in methanol was investigated under mild conditions. The results show that Ni-B/SiO2 significantly catalyzed DMSLLR hydroconversion by increasing the methanol-extractable fraction of hydroconverted DMSLLR to 87.7% over Ni-B/SiO2 from 62.3% without catalyst. The yields of alkanes, hydroarenes, alkyl arenes, non-substituted arenes, organooxygen compounds, and organosulfur compounds from catalytic hydroconversion of DMSLLR are drastically higher than those from non-catalytic hydroconversion of DMSLLR. Benzo[ghi]perylene is the most abundant condensed arenes detected.

Solid superacid-catalyzed hydroconversion of an extraction residue from Lingwu bituminous coal

A solid superacid was prepared as a catalyst. The catalyst was characterized by ammonia temperature-programmed desorption, surface property measurement, and analyses with scanning electron microscopy and Fourier transform infrared spectrometry. A extraction residue from Lingwu subbituminous coal was subject to non-catalytic and catalytic hydroconversion using cyclohexane as the solvent under pressurized hydrogen at 300°C for 3h. The results show that the total yield of petroleum ether-extractable arenes from catalytic hydroconversion is much higher than that from non-catalytic hydroconversion. The cleavage of Car–Calk bonds in the residue could significantly proceed during catalytic hydroconversion.

Microwave-assisted hydroconversions of demineralized coal liquefaction residues from Shenfu and Shengli coals

Microwave-assisted hydroconversions of demineralized coal liquefaction residues (DCLRs) from Shenfu (SF) and Shengli coals were investigated using methanol or ethanol as the solvent for both reaction and extraction. The results show that the solubilities of hydroconverted DCLRs in methanol under 0.7 MPa of initial hydrogen pressure (IHP) follow the order: non-catalytic hydroconversion = activated carbon-catalyzed hydroconversion < Pd/C-catalyzed hydroconversion < Ni-catalyzed hydroconversion; the solubility of Ni-catalyzed hydroconverted DCLR from SF coal in methanol increases with raising temperature up to 140 °C and with increase in IHP; the solubility of Ni-catalyzed hydroconverted DCLR from SF coal in methanol under 0.7 MPa of IHP at 130 °C is higher than that in ethanol. The molecular compositions of the extractable fractions were analyzed with GC/MS and the structural features of some extractable and inextractable fractions were characterized with FTIR.