Structures of the distillates obtained from hydrogenation and pyrolysis of Liddell coal

The structures of the distillable fractions (oils, b.p. >200 °C and volatile fractions, b.p. <200 °C) of the products from hydrogenation and pyrolysis of an Australian bituminous coal (Liddell) were investigated by gas chromatography-mass spectrometry (g.c.-m.s.) and nuclear magnetic resonance spectroscopy (n.m.r.). The distillable oil generated from hydrogenation of Liddell coal at 400 °C, using nickel molybdenum ortin (II) chloride as catalyst and tetralin or recycle oil as vehicle, consisted of a wide range of compounds. Long straight-chain alkanes were important components together with alkyl-substituted benzenes and tetralins, phenols and polycyclic material. When yields were low, as in the case of catalytic experiments with nickel molybdenum catalysts and no vehicle, isoprenoids could be identified. When a substantial proportion of the coal was converted to oil, branched-chain alkanes were not important components of the product. The replacement of tetralin and nickel molybdenum catalyst with stannous chloride reduced the amounts of methyl tetralins in the product. When tetralin was replaced by recycle oil, alkanes were more important components of the liquid products. Although alkenes were absent in oils generated by hydrogenation, they were important components of oils generated by pyrolysis. The highly volatile fractions (b.p. <200 °C) produced during hydrogenation consisted of alkyl-substituted benzenes, decalins, methylindan and straight-chain alkanes. Straight-chain alkanes were more abundant in those volatile fractions generated by hydrogenation with recycle vehicle than with tetralin. The Brown-Ladner method of estimating the fraction of aromatic carbon in distillable oils was adequate for less volatile fractions but was inadequate for the highly volatile fractions because of the large amounts of α-CH₃ and β-CH₃ alkyl groups present.     

双环戊二烯加氢NiMox/γ-Al2O3催化剂耐硫特性的研究

研究了钼元素及其添加量对镍基催化剂在双环戊二烯（DCPD）加氢反应中耐硫特性的影响规律。催化 剂∶DCPD =1∶10,反应温度150℃,压力3.5 MPa,转速600 r/min,噻吩浓度为：500 mg/L时,Ni/γ-Al₂O₃催化剂的双环戊二烯8、9位双键的加氢速率显著降低,3、4位双键的加氢活性完全抑制; 而NiMo_0.2/γ-Al₂O₃催化剂,在4 h内完成加氢反应,四氢双环戊二烯（endo-THDCPD）收率达到98%,抗硫特性显著提高。不同镍钼比的系列催化剂中,NiMo_0.2/γ-Al₂O₃具有最好的加氢活性与耐硫特性。0~2000 mg/L噻吩浓度内,低浓度条件下,NiMo_0.2/γ-Al₂O₃催化剂对双环戊二烯的加氢活性高,选择性好;随着噻吩浓度增加,催化性能有所下降,2000 mg/L时,加氢反应延长至6 h,endo-THDCPD收率降至95%。     

Effects of H2S and process conditions in the synthesis of mixed alcohols from syngas over alkali promoted cobalt-molybdenum sulfide

The present work is an investigation of how the process conditions influence the synthesis of mixed alcohols from syngas over a K₂CO₃/Co/MoS₂/C catalyst. The emphasis in the investigations is upon the effects of H₂S in the syngas feed. However the effects of the temperature and of the partial pressures of H₂ and CO are also investigated. With or without H₂S in the feed the pre-sulfided catalyst requires an initiation period to reach a stabilized behavior, but the duration of this period depends upon the H₂S level. Operation with a feed containing more than 103 ppmv H₂S leads to a fairly rapid stabilization of the product distribution and ensures that higher alcohols are the dominant reaction products. With less than 57 ppmv H₂S in the feed the stabilization of the product distribution is much slower, and methanol is the dominant product. An investigation of the reaction kinetics indicates a high CO coverage and low hydrogen coverage. Hydrogen sulfide in the syngas feed generally promotes chain growth for both alcohols and hydrocarbons, but lowers the alcohol selectivity by enhancing the hydrocarbon formation. The highest alcohol productivity reached in these investigations was 0.276 g/g cat./h, and this was achieved at 350 °C, 100 bar, GHSV = 5244 h⁻¹, Feed: 49.9 vol% H₂, 50.1 vol% CO. Finally it is found that sulfur fed to the reactor as H₂S is incorporated into the condensed alcohol product, and the incorporation of sulfur species into the product continues for some time after H₂S has been removed from the feed. When the catalyst is operated with an S-free syngas feed, the amount of sulfur in the condensed liquid product decreases over time, but after 35 h of operation with an S-free syngas the alcohol product still contains 340 ppmw of sulfur. Thiols appear to be the dominant sulfur compounds in the product.     

Olefins alkylation thiophenic sulfur of the real gasoline over the fluorinated Hbeta zeolite catalyst

The efficiency of the catalytic alkylation, the first step of the olefins alkylation thiophenic sulfur (OATS) process was investigated in three typical gasoline samples with different olefins contents over a fluorinated Hβ zeolite catalyst. Under the reaction conditions of 120 °C, 1.5 MPa and WHSV 0.5 h^− 1, over 95% light sulfur compounds in the feeds could be transformed to be heavier than the heptyl-thiophenes within a period of time-on-stream. The lifetime of the catalyst could prolong from 10 h to 26 h when the olefins content in the gasoline feed decreased from 40.87 wt.% to 9.20 wt.%. It was also found that the olefins content decrease was favorable for keeping and promoting the octane number by redistributing the components of the treated gasoline. In addition, the influence of the reaction conditions such as the temperature and WHSV on the efficiency of the catalytic alkylation was investigated.     

催化、动力学与反应器Pt/Y催化剂催化FCC柴油加氢制备BTX

利用Pt/Y催化剂,在固定床反应器中,温度380℃、压力3 MPa、氢油体积比1000及质量空速1.0 h^-1条件下,分别采用加氢处理的全馏分和轻馏分催柴为原料制备苯、甲苯和二甲苯（BTX）,获得（C₆+C₇+C₈）芳烃的总选择性分别为9.4%和33.9%。对原料和液体产物进行的气相色谱和质谱分析表明,BTX主要经过重芳烃的加氢饱和、裂解等反应生成,中间物质为烷基苯、四氢萘、茚满及茚类等单环芳烃。通过对反应原料以及对反应前后催化剂的N₂吸脱附、NH₃-TPD、XRD衍射图谱、TG等物化性质的表征,分析催化剂失活的主要原因。即全馏分催柴原料中高含量的S、N化合物快速吸附造成了催化剂中毒,而轻馏分原料中S、N化合物在催化剂表面的缓慢积累覆盖活性位,造成催化剂逐渐失活。     

Poisoning and Regeneration of an Ni/SiO2 Catalyst

The poisoning effect of thiophene during the hydrogenation of styrene on an Ni/SiO₂ catalyst, and the regenerating role of both pure hydrogen and 2-butyne in the presence of hydrogen on the poisoned catalyst, were studied. The treatments induced the elimination of sulfur and promoted an important recovery of the catalytic activity and selectivity. XPS analyses show that the sulfur species adsorbed during the catalyst poisoning is thiophene. Part of the sulfur remained irreversibly adsorbed after the regeneration treatments carried out at 473 K; a modification on the adsorbed sulfur electronic state was detected, which can be ascribed to thiophene hydrogenolysis induced by the regenerating temperature. © 1997 SCI.     

Selective hydrogenation of cyclopentadiene over supported metal catalysts

The selective hydrogenation of cyclopentadiene to cyclopentene has been studied in the liquid phase using Pd and Pd Me/Al₂O₃ bimetallic catalysts (Me = Mn, Ni, Co, W). The highest activity was obtained with Pd Co and Pd W/Al₂O₃. For these catalysts, no hydrogen or CO chemisorption was detected although Pd could be seen by XPS at 335·8 eV; it is considered that new species, more active for the selective hydrogenation of cyclopentadiene, appeared at the catalyst surface. The sulfur resistance towards thiophene has also been studied. It was observed that the highest sulfur resistance is coincident with the highest activity. XPS analysis shows that the poisoning species is thiophene adsorbed on the catalyst surface.     

Influence of the source of sulfur on the hydroconversion of 1-methylnaphthalene over a Pt–Pd/USY catalyst

Hydroconversion of 1-methylnaphthalene was performed over a Pt–Pd/USY catalyst in a batch reactor at 310 °C and 5 MPa of hydrogen pressure in cyclohexane as the solvent and in the presence of 800 ppm of sulfur resulting from different sources, hydrogen sulfide, thiophene and dibenzothiophene. In a general manner, hydrogenation of 1-methylnaphthalene into the corresponding mixture of methyltetralines is not significantly affected by the nature of the sulfur species present in the starting feed. On the contrary, going from hydrogen sulfide to thiophene and finally to dibenzothiophene, hydrogenation of methyltetralines into methyldecalines is lowered and ring-opening of methyltetralines to alkylbenzenes is enhanced. This would agree with the expected sequence of appearance of hydrogen sulfide in the feed.These results are in agreement with dissociation of hydrogen into protonic and hydride species, as already proposed in the presence of sulfided catalysts, i.e., protonic species would be involved for the hydrogenation steps and hydride species for the ring-opening steps. Hydrogen sulfide present as such or resulting from the transformation of thiophene or dibenzothiophene would then reduce the hydrogenation route, and, as a consequence, increase the hydrogenolysis route.     

Novel mesoporous aluminosilicate supported palladium-rhodium catalysts for diesel upgrading: II. Catalytic activity and improvement of industrial diesel feedstocks

Bimetallic PdRh catalysts (molar ratio Pd/Rh = 1 and 2) were prepared by impregnation of a mesoporous aluminosilicate (molar ratio Si/Al = 10 and 20). These materials are destined to be used in industrial processes aiming to improve diesel quality by hydrogenation and ring-opening of aromatic components. The four catalysts were examined for their activity in hydrogenation of naphthalene and tetralin model feedstocks, at 6 MPa, including in the presence of sulfur containing compounds. The capacity of one of these catalysts to improve the quality of hydrogenated industrial light cycle oil containing ≤50 wt ppm of sulfur was evaluated in a pilot plant. In these industrial conditions, the catalyst has a higher catalytic activity at lower temperature than a reference state of-the-art catalyst, giving a seven-point improvement of the cetane number at 280–300 °C and with formation of less than 10% of non-selective cracking products.     

Rhodium nanoparticles intercalated into montmorillonite for hydrogenation of aromatic compounds in the presence of thiophene

Rhodium metal nanoparticles intercalated into montmorillonite (Rh-MMT) have been prepared and used for the hydrogenation of benzene and other aromatic compounds. Rh-MMT was characterized by PXRD, TEM and ICP-AES. The crystallite size of the rhodium particles was 6.9 nm using PXRD and the particle size by TEM was 25.6 ± 2.5 nm. Benzene hydrogenation was carried out at different substrate/catalyst mass ratios, temperature and pressure to optimize the reaction conditions. The benzene is completely hydrogenated with 100% selectivity to cyclohexane at 453 K and 6.2 MPa. The catalyst was poisoned by thiophene, and benzene hydrogenation decreased with increasing thiophene concentration. Hydrogenation of toluene, o,m,p-xylenes, naphthalene and anthracene were also carried out at the optimized reaction conditions.     

Experimental study on two-stage catalytic hydroprocessing of middle-temperature coal tar to clean liquid fuels

Special Mo–Co/γ-Al₂O₃ and W–Ni/γ-Al₂O₃ catalysts with different metal loadings were prepared applying new synthesis technologies that combine ultrasonic-assisted impregnation and temperature-programming methods. Clean liquid oil was obtained from middle-temperature coal tar via hydrogenation in two-stage fixed beds filled with the laboratory made catalysts. The Mo–Co/γ-Al₂O₃ catalyst with 12.59 wt.% Mo and 3.37 wt.% Co loadings, and the W–Ni/γ-Al₂O₃ catalyst with 15.75 wt.% W and 2.47 wt.% Ni loadings were selected. The effects of pressure and liquid hourly space velocity on hydrogenation performance were investigated while other experimental conditions remained constant. Gasoline (?180 °C) and diesel (180–360 °C) fractions were separated from the oil product and analyzed. The two-stage reacting system was capable of removing nitrogen and sulfur from 1.69 and 0.98 wt.% in the feed to less than 10 ppm and 100 ppm, respectively in the products. The results indicated that the raw coal tar could be considerably upgraded through catalytic hydroprocessing and high-quality fuels were obtained.     

Preliminary study on mechanism of naphthalene hydrogenation to form decalins via tetralin over Pt/TiO2

To clarify the mechanism of naphthalene hydrogenation to cis- and trans-decahydronaphthalene (decalins) via tetrahydronaphthalene (tetralin), the rate of naphthalene hydrogenation was compared with those of tetralin and tetralin containing 3–10 mol% naphthalene over a TiO₂-supported Pt catalyst. Tetralin was hydrogenated to decalins readily, while the naphthalene hydrogenation did not take place under the same reaction conditions (433 K and 2.96 MPa). When 3–10 mol% naphthalene was added to tetralin, the rate of hydrogenation decreased clearly with an increase of naphthalene content. The observation suggests that naphthalene interacts with surface metals strongly and prevents the hydrogenation of tetralin.     

Deep hydrodesulphurization and hydrogenation of diesel fuels on alumina-supported and bulk molybdenum carbide catalysts

Deep hydrodesulphurization (HDS) of diesel fuels has been carried out on P (Ni)-promoted or non-promoted Mo₂C-supported γ-Al₂O₃ and bulk Mo₂C under standard industrial conditions (613 K, 3 MPa). The effect of the promoter was investigated for different feedstocks on HDS and hydrogenation (HYD) with very low levels of sulfur. The temperature effect was also followed. The HDS conversion indicates that phosphorus promoted alumina supported carbide catalysts are as active as a commercial Co-Mo/Al₂O₃ catalyst for low levels of sulfur in the feed. Furthermore, the refractory compounds such as 4,6-dimethyldibenzothiophene are only transformed on molybdenum carbide catalyst in industrial conditions for hydrotreated gas oils. With gas oils with less than 50 wt ppm in sulfur, phosphorus promoted molybdenum carbide catalysts become more active than commercial catalysts for the HYD of the aromatic compounds and the HDS or the HDN of the feedstock.     

Selective hydrogenation of styrene. II. Poisoning of Pd/Al2O3 by thiophene and pyridine

The poisoning of a commercial Pd/Al₂O₃ catalyst by pyridine and thiophene during the selective hydrogenation of styrene to ethylbenzene was studied. It was found that the Pd electronic state is the main factor controlling the interaction between the metal and the poisons. Pyridine added to the non-poisoned feed in a pulse produces a modification in the Pd electronic state and a decrease in conversion, but, within certain limits, inhibits the adsorption of more pyridine or thiophene molecules.     

Mesoporous silica–alumina as support for Pt and Pt–Mo sulfide catalysts: Effect of Pt loading on activity and selectivity in HDS and HDN of model compounds

The potential of mesoporous silica–alumina (MSA) material as support for the preparation of sulfided Pt and Pt–Mo catalysts of varying Pt loadings was studied. The catalysts were characterized by their texture, hydrogen adsorption, transmission electron microscopy, temperature programmed reduction (TPR) and by activity in simultaneous hydrodesulfurization (HDS) of thiophene and hydrodenitrogenation (HDN) of pyridine. Sulfided Pt/MSA catalysts with 1.3 and 2 wt.% Pt showed almost the same HDS and higher HDN activities per weight amounts as conventional CoMo and NiMo/Al₂O₃, respectively. The addition of Pt to sulfided Mo/MSA led to promotion in HDS and HDN with an optimal promoter content close to 0.5 wt.%. The results of TPR showed strong positive effect of Pt on reducibility of the MoS₂ phase which obviously reflects in higher activity of the promoted catalysts. The activity of the MSA-supported Pt–Mo catalyst containing 0.5 wt.% Pt was significantly higher than the activity of alumina-supported Pt–Mo catalyst. Generally, Pt–Mo/MSA catalysts promoted by 0.3–2.3 wt.% Pt showed lower HDS and much higher HDN activities as compared to weight amounts of CoMo and NiMo/Al₂O₃. It is proposed that thiophene HDS and pyridine hydrogenation proceed over Pt/MSA and the majority of Pt–Mo/MSA catalysts on the same type of catalytic sites, which are associated with sulfided Pt and MoS₂ phases. On the contrary, piperidine hydrogenolysis takes place on different sites, most likely on metallic Pt fraction or sites created by abstraction of sulfur from MoS₂ in the presence of Pt.     

高温下工业NiW/Al2O3催化剂上萘的加氢饱和反应

在中压固定床中,高温条件下研究了工业NiW/Al2O3催化剂上硫化氢气氛中反应温度、反应压力和空速对萘加氢饱和反应过程的影响。实验结果表明,在液时空速为10—30 h-1,氢油体积比为800,高反应温度区320—380℃的实验条件下,萘加氢主要生成四氢萘和十氢萘,而进一步加氢裂化产物较少;提高反应温度,萘转化率和四氢萘的收率下降,加氢裂化产物略有升高,表明高温不利于芳环的加氢饱和;提高加氢反应压力,萘的转化率和四氢萘的芳环加氢程度提高;综合反应结果,提出了高温条件下萘加氢的简化可逆连串反应途径。     

Activity and stability studies of MoO2 catalyst for the partial oxidation of gasoline

The present investigation is focused on the performance of molybdenum dioxide (MoO₂) as a catalyst for the partial oxidation of isooctane. Metallic character and high oxygen mobility exhibited by this oxide appear to enhance its catalytic activity, which can be explained in terms of the Mars–van Krevelen mechanism. An oxygen-to-carbon ratio (O/C) of 0.72 seems to stabilize the catalytic performance, which could reach H₂ yields of 78% and carbon conversions of 100%, at 700 °C and 1 atm, after 20 h on stream. In addition, the catalyst was tested for sulfur tolerance using thiophene as model sulfur compound. Our findings indicate that the catalytic activity is barely affected even at sulfur concentrations as large as 500 ppm, after 7 h on stream. Finally, the catalyst performance was compared to that of a nickel catalyst using premium gasoline as fuel. MoO₂ displayed a stable performance whereas the Ni catalyst deactivated due to coke formation.     

Kinetic behavior of hydrogenation of aromatics in diesel fuel over silica–alumina-supported bimetallic Pt–Pd catalyst

The kinetics and long-term stability test of the aromatic hydrogenation of diesel fuel were studied on SiO₂–Al₂O₃ supported bimetallic Pt–Pd catalyst. The tests on the influence of operating parameters and kinetics studies were carried out using Pt (0.5 wt.%)–Pd (1.0 wt.%)/SiO₂–Al₂O₃, which provided the highest catalytic activity in a previous paper [Applied Catalysis A: General, 192 (2000) 253] with hydrotreated light cycle oil (LCO)/straight-run light gas oil (SRLGO) feedstocks containing 30 vol.% aromatics/100 wppm sulfur and 34 vol.% aromatics/420 wppm sulfur under numerous conditions. The results on this catalyst obtained at different LHSV showed an excellent fit to first-order kinetics. The apparent activation energy was determined to be 92 kJ/mol. Long-term stability test demonstrated the excellent stability of this catalyst. The products during the long-term stability test are of good quality, with the upgraded color, the increased cetane index, and sufficiently decreased sulfur content.     

Sodium and hydrogen tetrachloroaluminate catalysts for molecular weight reduction of hydrocarbons

Sodium and hydrogen tetrachloroaluminates (NaAlCl₄ and HAlCl₄) have been evaluated as catalysts for the molecular weight reduction of hydrocarbons. The NaAlCl₄ is the major molecular weight reduction and synthesis component, and HAlCl₄ adds a hydrogenation function. The optimum catalyst composition, for the petroleum AC-20 resid and shale oil feeds studied, was found to be 2.5–4.5 wt.% HAlCl₄ in NaAlCl₄. To convert these feeds completely into gasoline range materials, a hydrogen partial pressure and a hydrogen consumption of 950 psia and 900 scf/bbl, respectively, are estimated to be required. About 40% of the hydrogen consumption would be for contaminant removal. Above a hydrogen partial pressure of about 450 psia, the liquid products produced contained less than 100 ppm each of sulfur and nitrogen contaminants. The C₆C₁₃ molecular weight portion of the liquid products contained about 55% aromatics, 8% naphthenes, 33% branched paraffins and 4% normal paraffins (weight basis).     

Hydrogenation of the inertinite macerals of Bayswater coal

Yields of products from the hydrogenation of the inertinite and vitrinite+exinite macerals of the Bayswater (New South Wales, Australia) coal in a batch autoclave were investigated. Samples were hydrogenated for 1 h at 400 and 450 °C with tetralin as vehicle, hydrogen as charge gas and no added catalyst. The results show that the inertinite macerals contributed significantly to the liquid hydrogenation products, in particular to the oil yield obtained at 450 °C.