A series of metal-modified HZSM-5 catalysts were prepared by impregnation and were used for ethylbenzene dealkylation of the mixed C8 aromatics(ethylbenzene,m-xylene and o-xylene).The effects of different supported me...A series of metal-modified HZSM-5 catalysts were prepared by impregnation and were used for ethylbenzene dealkylation of the mixed C8 aromatics(ethylbenzene,m-xylene and o-xylene).The effects of different supported metals(Pt,Pd,Ni,Mo)on catalytic performance,including reaction conditions,were investigated.The physicochemical properties of catalysts were characterized by means of XRD,BET,TEM and NH_(3)-TPD.Experimental results showed that metallic modification obviously increased the ethylbenzene conversion and reduced the coke deposition,greatly improving the catalyst stability.The distinction of ethylbenzene conversion depended on the interaction between hydrogenation reactivity and acidic cracking of bifunctional metal-modified zeolites.Compared with Pt and Ni,Pd and Mo were easier to disperse into HZSM-5 micropores during loading metals.The acidic density of different metal-modified HZSM-5 declined in the following order:HZSM-5>Pt/HZSM-5>Pd/HZSM-5>Ni/HZSM-5>Mo/HZSM-5.The activity of ethylene hydrogenation decreased with Pt/HZSM-5>Pd/HZSM-5>Ni/HZSM-5>Mo/HZSM-5.In comparison,Pd/HZSM-5 showed the best catalytic performance with both high activity and high selectivity,with less cracking loss of m-xylene and o-xylene.Moreover,the following reaction conditions were found to be preferable for ethylbenzene dealkylation over Pd/HZSM-5:340℃,1.5 MPa H2,WHSV 4 h^(−1),H_(2)/C84 mol/mol.展开更多
Geoporphyrins, isolated from source rock, were analyzed on electron ionization mass spectrometry （EIMS） and Tandem mass spectrometry （MS/MS）. The spectrum of ElMS shows that the geoporphyrins are mainly composed o...Geoporphyrins, isolated from source rock, were analyzed on electron ionization mass spectrometry （EIMS） and Tandem mass spectrometry （MS/MS）. The spectrum of ElMS shows that the geoporphyrins are mainly composed of two types: DPEP and eito. Most of the porphyrin carbon numbers are greater than C<sub>32</sub>. The daughter spectra of the molecular ions (C<sub>34-36</sub>DPEPs) display the loss of methyl and ethyl groups, which indicate there are ethyl and propyl groups in the mother ions. The average condensed structural formulae, derived from the data of the spectra on MS/MS, have clearly shown the composition of the substituents on the porphyrin pyrrole ring, and the regular changes of the substituents reveal the characteristics of the dealkylation of the porphyrins in the geosphere.展开更多
Cumene is an important intermediate and chemical in chemical industry. In this work, directional preparation of cumene using lignin was achieved by a three-step cascade process. The mixture aromatics were first produc...Cumene is an important intermediate and chemical in chemical industry. In this work, directional preparation of cumene using lignin was achieved by a three-step cascade process. The mixture aromatics were first produced by the catalytic pyrolysis of lignin at 450 ℃ over I%Zn/HZSM-5 catalyst, monocyclic aromatics with the selectivity of 85.7 wt% were obtained. Then, the catalytic dealkylation matics with 93.6 wt% benzene at 600 ℃ of heavier aromatics resulted in benzene-rich aro- over Hβ catalyst. Finally, the cumene synthesis was performed by the aromatic alkylation, giving cumene selectivity of 91.6 C-tool% using the [bmim]Cl-2AlCl3 ionic liquid at room temperature for 15 min. Besides, adding a small amount of methanol to the feed can efficiently suppress the coke yield and enhance the aromatics yield. The proposed transformation potentially provides a useful route for production of cumene using renewable lignin.展开更多
In the present work, we reported a novel route for the conversion of lignocellulosic biomass （sawdust） to a high-value chemical of benzoic acid under atmospheric pressure. The trans- formation involved the catalytic...In the present work, we reported a novel route for the conversion of lignocellulosic biomass （sawdust） to a high-value chemical of benzoic acid under atmospheric pressure. The trans- formation involved the catalytic pyrolysis of sawdust into aromatics, the decomposition of heavier alkylaromatics to toluene, and the liquid-phase oxidation of toluene-rich aromatics to benzoic acid. The production of the desired benzoic acid from the sawdust-derived aro- matics, with the benzoic acid selectivity of 85.1 C-mol% and nearly complete conversion of toluene, was achieved using the MnO2/NHPI catalyst at 100 ℃ for 5 h. The in uence of adding methanol on the catalytic conversion of sawdust to the core intermediate of toluene was also investigated in detail.展开更多
基金supported by the National Natural Science Foundation of China(Nos.20873091,51174277)China National Petroleum Corporation Innovation Research Funds(No.2012D-5006-0505).
文摘A series of metal-modified HZSM-5 catalysts were prepared by impregnation and were used for ethylbenzene dealkylation of the mixed C8 aromatics(ethylbenzene,m-xylene and o-xylene).The effects of different supported metals(Pt,Pd,Ni,Mo)on catalytic performance,including reaction conditions,were investigated.The physicochemical properties of catalysts were characterized by means of XRD,BET,TEM and NH_(3)-TPD.Experimental results showed that metallic modification obviously increased the ethylbenzene conversion and reduced the coke deposition,greatly improving the catalyst stability.The distinction of ethylbenzene conversion depended on the interaction between hydrogenation reactivity and acidic cracking of bifunctional metal-modified zeolites.Compared with Pt and Ni,Pd and Mo were easier to disperse into HZSM-5 micropores during loading metals.The acidic density of different metal-modified HZSM-5 declined in the following order:HZSM-5>Pt/HZSM-5>Pd/HZSM-5>Ni/HZSM-5>Mo/HZSM-5.The activity of ethylene hydrogenation decreased with Pt/HZSM-5>Pd/HZSM-5>Ni/HZSM-5>Mo/HZSM-5.In comparison,Pd/HZSM-5 showed the best catalytic performance with both high activity and high selectivity,with less cracking loss of m-xylene and o-xylene.Moreover,the following reaction conditions were found to be preferable for ethylbenzene dealkylation over Pd/HZSM-5:340℃,1.5 MPa H2,WHSV 4 h^(−1),H_(2)/C84 mol/mol.
文摘Geoporphyrins, isolated from source rock, were analyzed on electron ionization mass spectrometry （EIMS） and Tandem mass spectrometry （MS/MS）. The spectrum of ElMS shows that the geoporphyrins are mainly composed of two types: DPEP and eito. Most of the porphyrin carbon numbers are greater than C<sub>32</sub>. The daughter spectra of the molecular ions (C<sub>34-36</sub>DPEPs) display the loss of methyl and ethyl groups, which indicate there are ethyl and propyl groups in the mother ions. The average condensed structural formulae, derived from the data of the spectra on MS/MS, have clearly shown the composition of the substituents on the porphyrin pyrrole ring, and the regular changes of the substituents reveal the characteristics of the dealkylation of the porphyrins in the geosphere.
文摘Cumene is an important intermediate and chemical in chemical industry. In this work, directional preparation of cumene using lignin was achieved by a three-step cascade process. The mixture aromatics were first produced by the catalytic pyrolysis of lignin at 450 ℃ over I%Zn/HZSM-5 catalyst, monocyclic aromatics with the selectivity of 85.7 wt% were obtained. Then, the catalytic dealkylation matics with 93.6 wt% benzene at 600 ℃ of heavier aromatics resulted in benzene-rich aro- over Hβ catalyst. Finally, the cumene synthesis was performed by the aromatic alkylation, giving cumene selectivity of 91.6 C-tool% using the [bmim]Cl-2AlCl3 ionic liquid at room temperature for 15 min. Besides, adding a small amount of methanol to the feed can efficiently suppress the coke yield and enhance the aromatics yield. The proposed transformation potentially provides a useful route for production of cumene using renewable lignin.
文摘In the present work, we reported a novel route for the conversion of lignocellulosic biomass （sawdust） to a high-value chemical of benzoic acid under atmospheric pressure. The trans- formation involved the catalytic pyrolysis of sawdust into aromatics, the decomposition of heavier alkylaromatics to toluene, and the liquid-phase oxidation of toluene-rich aromatics to benzoic acid. The production of the desired benzoic acid from the sawdust-derived aro- matics, with the benzoic acid selectivity of 85.1 C-mol% and nearly complete conversion of toluene, was achieved using the MnO2/NHPI catalyst at 100 ℃ for 5 h. The in uence of adding methanol on the catalytic conversion of sawdust to the core intermediate of toluene was also investigated in detail.
