Deep desulfurization of gasoline using ion-exchange zeolites: Cu(I)- and Ag(I)-beta

Solid adsorbents Cu(I) and Ag(I) metal exchanged beta zeolites were prepared by solid-state ion-exchange (SSIE) method. Crystallographic structure of the prepared adsorbents has been characterized by XRD analysis. The texture of the prepared adsorbents was investigated using N₂ sorption. Pyridine IR measurements have been carried out to investigate the nature of the acid sites of the adsorbents. The deep-desulfurization performance of such adsorbents has been evaluated through fixed-bed adsorption technique with model gasoline containing thiophene and benzothiophene at ambient temperature and pressure. The obtained results revealed that the breakthrough capacities of Cu(I)- and Ag(I)-beta zeolite with the optimized Cu⁺ or Ag⁺ content are 0.239 mmol S/g and 0.237 mmol S/g, respectively. The remaining sulfur in the desulfurized gasoline is less than 1 ppmw. Their desulfurization capacity for actual FCC gasoline blend is reduced about 30% due to the competitive adsorption from olefins and aromatics. However, The capacity regeneration of Cu(I)- and Ag(I)-beta zeolite sorbents was carried out for 9 times. It is more than 95% recovery of desulfurization after the first regeneration, and it keeps little reduction after subsequent 8 times of regeneration. Such studies included the effect factors on desulfurization performance, such as metal exchange content, SiO₂/Al₂O₃ ratio, acidity, and other texture properties of the zeolite etc.     

Adsorption of thiophene and toluene on NaY zeolites exchanged with Ag(I), Ni(II) and Zn(II)

The present study evaluates the adsorption capacity of thiophene and toluene and their competitive behaviour on zeolite NaY exchanged with transition metals (5 wt% Ni, Zn and Ag). The headspace chromatography technique was used to obtain monocomponent apparent adsorption isotherms of thiophene and toluene with NaY, NiY, ZnY and AgY using isooctane as an inert solvent at 30 and 60 °C. Selectivity between toluene and thiophene at saturation capacities were also measured at 30 °C. The adsorption capacity for thiophene increased for the studied adsorbents as follows: NaY < ZnY < NiY < AgY at 30 °C and NaY < NiY < ZnY < AgY at 60 °C. Toluene is less adsorbed, but within the same order of magnitude as thiophene and following the same sorbent order. All adsorbents were moderately selectivity for toluene. Nevertheless, the sulfur content was successfully reduced in the presence of aromatics and olefins in immersion tests with a model fuel mixture. These results show the importance of inserting transitions metals in the zeolitic structure to enhance the adsorption of both aromatic and sulfur containing compounds in organic liquid mixtures, which shows promise to meet environmental standards in transportation fuels.     

流化催化裂化汽油吸附脱硫金属氧化物吸附剂

制备了不同的金属氧化物吸附剂并采用不同方法进行改性,在常压、温度为360℃、液时空速为1 h-1的条件下,采用固定床吸附法考察了吸附剂改性前后的脱硫性能.结果表明:MoO3和MnO2的脱硫效果较好,对硫含量为511.10 μg/g的流化催化裂化(FCC)汽油脱硫,脱硫率达60%以上;CuO-MoO3,MoO3-MgO和MoO3-Fe2O3复合金属氧化物吸附剂对FCC汽油的脱硫效果可达75%以上,其中脱除乙硫醇效果最好的是CuO-MoO3,脱除噻吩效果最好的是MoO3-MgO,脱除二苯并噻吩效果最好的是MoO3-Fe2O3;采用等体积浸渍法对MoO3和MnO2改性后,对FCC汽油吸附脱硫效果有所增强,其中对MoO3改性效果较好的是NiO,脱硫率可达90.1%,对MnO2改性效果较好的是CoO,脱硫率可达93.2%.     

Partial oxidation (POX) reforming of gasoline for fuel-cell powered vehicles applications

As a part of the development of a gasoline processor for integration with a proton-exchanged membrane (PEM) fuel cell, we carried out the POX reforming reaction ofiso-octane, toluene and gasoline over a commercial methane reforming catalyst, and investigated the reaction conditions required to prevent the formation of carbon and the effect of fuel constituents and sulfur impurities in gasoline. The H₂ and CO compositions increased with increasing reaction temperature, while those of CO₂ and CH₄ decreased. It is desirable to maintain an O/C molar ratio of more than 0.6 and an H₂O/C molar ratio of 1.5 to 2.0 for vehicle applications. It has been found that carbon formation in the POX reforming ofiso-octane occurs below 620 °C, whereas in the case of toluene it occurs below 640 °C. POX reforming of gasoline constituents led to the conclusion that hydrogen production is directly related to the constituents of fuels and the operating conditions. It was also found that the coke formation on the surface of catalysts is promoted by sulfur impurities in fuels. For the integration of a fuel processor with PEM fuel cell, studies are needed on the development of new high-performance transition metal-based catalysts with sulfur and coke-resistance and the desulfurization of fuels before applying the POX reformer based on gasoline feed.     

红外光谱法研究烯烃对Ce（Ⅳ）Y分子筛脱硫效果的影响

选取1-辛烯、1,5-己二烯、环己烯等作为模拟汽油中的烯烃模型化合物,采用FT-IR方法得到饱和吸附不同模拟油之后的Ce（Ⅳ）Y分子筛的红外光谱图,根据红外光谱信息研究烯烃对Ce（Ⅳ）Y分子筛选择性吸附脱硫性能的影响。研究发现,Ce（Ⅳ）Y分子筛阳离子和烯烃的双键发生了σ-π络合,从而跟与Ce（Ⅳ）Y存在SM作用的噻吩形成了竞争吸附。在含烯烃的模拟油中,由于烯烃和分子筛发生相互作用,占据了吸附剂的活性位,导致Ce（Ⅳ）Y分子筛的脱硫性能显著降低。     

Thiophene conversion under mild conditions over a ZSM-5 catalyst

Refiners are nowadays actively considering the post-treating FCC gasoline processes as a viable and less costly approach for meeting sulfur environmental regulations. Most promising catalytic desulfurization processes do not require hydrogen addition, including between others the use of zeolites as adsorbents/catalysts. This type of desulfurization leads to the formation of significant amounts of coke, requiring keeping high catalyst activity a continuous twin fluidized bed system (fluidized-bed reactor, fluidized bed regenerator). This study evaluates the catalytic conversion of thiophene and/or thiophene in n-octane mixtures. Catalytic experiments are carried out in the CREC riser simulator under mild conditions, using H-ZSM5 zeolite dispersed in a silica matrix. The experimental results obtained demonstrate a higher selective conversion of thiophene over n-octane. It is shown that thiophene conversion proceeds via ring opening and alkylation yielding H₂S, alkyl-thiophenes, benzothiophene, and coke, with no measurable thiophene saturation or dimerization reactions observed. The experimental results are also supported with an extensive thermodynamic analysis that includes all the possible thiophene conversion pathways over zeolites. On this basis and using as a reference the observable measurable species, a reaction network is proposed to represent the thiophene catalytic conversion under the suggested gasoline post treatment conditions.     

Production of synthesis gas by autothermal reforming of iso-octane and toluene over metal modified Ni-based catalyst

The reforming process of gasoline is an attractive technique for fuel processor or hydrogen station applications. We investigated catalytic autothermal reforming (ATR) of iso-octane and toluene over transition metal supported catalysts. The catalysts were prepared by an incipient wetness impregnation method and characterized by N₂ physisorption, XRD, and TEM techniques before and after the reaction. Many of the tested catalysts displayed reasonably good activity towards the reforming reactions of iso-octane. Especially, Ni/Fe/MgO/Al₂O₃ catalyst showed more activity than the other catalysts tested in this study including commercial HT catalyst. Ni/Fe/MgO/Al₂O₃ catalyst showed good stability for 700 h in the ATR of iso-octane. No major change was observed in catalytic activity in ATR of iso-octane or in the structure of catalyst. Since iso-octane, toluene are surrogates of gasoline, Ni/Fe/MgO/Al₂O₃ catalyst can be considered as ATR catalyst for gasoline fuel processor and hydrogen station systems.     

负载金属球形活性炭的制备及其噻吩吸附性能

以122型酚醛型弱酸性阳离子交换树脂为原料,首先进行阳离子交换,然后经炭化-活化制备了负载Ag、Cu和Ni等金属的球形活性炭材料,所得材料的孔结构和负载金属的形态分别采用低温N2吸附、X射线衍射和扫描电镜等方法进行了表征,结果表明制备的负载金属球形炭材料中金属以单质颗粒的形态存在,而其比表面积和孔容比未负载的材料略为下降。以噻吩-环己烷模拟溶液为考察对象,采用动态吸附方法,以穿透硫容为考察指标,评价了材料的吸附脱硫性能,并初步分析了其吸附机理。负载的球形炭材料的穿透硫容为1.46 mg&#8226;g^-1,而负载Ag、Cu和Ni金属颗粒的球形炭材料的穿透硫容分别提高到3.66、4.43、5.07 mg&#8226;g^-1。     

负载金属氧化物分子筛催化氧化模拟汽油的脱硫研究

A simulated gasoline consisting of model sulfur compounds of thiophene （C4H4S） and 3-methythiophene （3-MC4H4S） dissolved in n-heptane was tested for the oxidative desulfurization in the hydrogen peroxide （H202） and formic acid oxidative system over metal oxide-loaded molecular sieve. The effects of the oxidative system, loaded metal oxides, phase transfer catalyst, the addition of olefin and aromatics on sulfur removal were investigated in details. The results showed that the sulfur removal rate of simulated gasoline in the H202/formic acid system was higher than in other oxidative systems. The cerium oxide-loaded molecular sieve was found very active catalyst for oxidation of simulated gasoline in this system. The sulfur removal rates of C4H4S and 3-MC4H4S were enhanced when phase transfer catalyst （PTC） was added. However, the sulfur removal rate of simulated gasoline was reduced with the addition of olefin and aromatics.     

Selective oxidation of H<Subscript>2</Subscript>S to sulfur over CeO<Subscript>2</Subscript>-TiO<Subscript>2</Subscript> catalyst

The catalytic oxidation of hydrogen sulfide (H₂S) to elemental sulfur was studied over CeO₂-TiO₂ catalysts. The synthesized catalysts were characterized by various techniques such as X-ray diffraction, BET, X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of ammonia, and scanning electron microscopy (SEM). Catalytic performance studies of the CeO₂-TiO₂ catalysts showed that H₂S was successfully converted to elemental sulfur without considerable emission of sulfur dioxide. CeO₂-TiO₂ catalysts with Ce/Ti=1/5 and 1/3 exhibited the highest H₂S conversion, possibly due to the uniform dispersion of metal oxides, high surface area, and high amount of acid sites.     

Effect of the acid-base properties of additives for a cracking catalyst on the sulfur content in liquid products

The effect of the nature and methods for the production of additives for a cracking catalyst on the sulfur content in liquid cracking products was studied. The influence of the acid-base properties of the additives for a cracking catalyst on the redistribution of sulfur raw material between gaseous and liquid products, including that in a gasoline fraction with T _EP = 200°C, is analyzed. It is shown that, in contrast to the earlier concept of the approach to choosing such additives, we must consider not only the effect of the acid-base properties of additives but also the aromatization reactions facilitating the formation of hydrogenated thiophene derivatives, which are unstable under catalytic cracking conditions. It is shown that an increase in the additive acidity promotes the reduction of the residual sulfur content in liquid cracking products. The enhancement of both the strength and the concentration of basic sites does not reduce the sulfur content. The simultaneous presence of acidic and basic sites in the structure of a mixed Mg-Al oxide with a spinel structure affords deeper sulfur-refinement of gasoline than the presence of only acidic sites. Oxides of a series of metals (Zn, Zr, Cr, Ce, Cu, Ca, Mg, Al) with variable acid-base properties were used as an additive for a LYUKS cracking catalyst (OAO Gazpromneft’-ONPZ). The data obtained allows us to develop new cracking catalysts (or additives for already existing catalysts) that facilitate the production of motor fuels (gasoline) answering the more stringent requirements for sulfur content.     

Polyborane-derived metal borides. 1. Hydrodesulphurization catalysts with potential for coal liquefaction

A new class of metal borides prepared at elevated temperatures and under hydrogen pressure from borane anions and cobalt or nickel salts catalyse the hydrodesulphurization of thiophene at 400 °C to butane and H₂S. The most active catalysts are prepared from the anions NaB₅H₈ and NaB₁₀H₁₃. These borides have unusually high boron levels (12–17%) and exhibit high sulphidation resistances. Using these catalysts, 88–99% conversion of thiophene is observed. With less active catalyst systems or at lower temperatures, butene and tetrahydrothiophene are also produced. Under similar reaction conditions, the nickel-pentaborane derived catalyst promotes 93% hydrogenolysis of furan. The boride catalysts do not promote hydrogenation of non-heterocyclic aromatics such as toluene and ethylbenzene. The potential of these new boride systems in processes related to coal liquefaction is discussed.     

Partial Oxidation Reforming Catalyst for Fuel Cell-Powered Vehicles Applications

Transition metal oxide formulations for the partial oxidation (POX) reforming of isooctane were investigated for an onboard gasoline fuel processor. Ni/M/MgO/Al₂O₃ systems are more active than a commercial ICI catalyst. These catalysts showed better sulfur tolerance over the commercial ICI catalyst in the POX reforming of isooctane containing sulfur (Cs = 100 ppm). There was no apparent deactivation or modification of structure during 770h onstream. It was found that Ni/(Fe,Co)/MgO/Al₂O₃ catalyst is a promising candidate as POX reforming catalyst for gasoline fuel processor applications.     

Effects of textural parameters and noble metal loading on the catalytic activity of cryptomelane-type manganese oxides for formaldehyde oxidation

Nanoporous manganese oxides were synthesized by a sol–gel method with maleic acid as an organic reducing agent. Noble metals (Pt and Ag) were then loaded by an impregnation method. The as-prepared materials are tunneled manganese oxides, cryptomelane (K-OMS-2). Further characterization was performed using X-ray diffraction (XRD), transmission electron microscopy (TEM) and N₂ adsorption/desorption techniques. The structure and textural properties are heavily dependent on reaction conditions. Reaction solutions using low temperature produced well-crystallized nanorods, whereas solutions at high temperature yielded poorly-crystallized nanoparticles. Formaldehyde oxidation was carried out to evaluate the catalytic activity of these materials. The cryptomelane nanoparticles that possess higher specific surface area and more open pores showed better catalytic performance than the cryptomelane nanorods. Effects of Pt and Ag on the cryptomelane catalysts indicate that not only noble metal types, but also the existence form of metals on the catalyst surface greatly affects the catalytic activity. Pt/K-OMS-2 consisting of ca. 2 nm Pt nanoparticles presents higher activity than Ag/K-OMS-2, but lower activity than the corresponding cryptomelane materials without metal loading, due to the cover of Pt on the active sites of manganese oxides.     

载金属离子的13X分子筛对噻吩的吸附性能研究

采用Zn2+,Cu2+,N i2+,Ag+分别负载到13X分子筛制得吸附剂,考察了它们对噻吩的吸附能力,发现Ag+-13X吸附效果最好,与软硬酸碱理论解释的结果一致。测定了噻吩在Ag+-13X上的吸附动力学数据,并测定了其不同温度下的吸附平衡数据,采用Langmu ir模型进行拟合,与平衡数据吻合得很好,说明Langmu ir模型能够描述本体系的特征,从微观上探讨了其吸附机理,是分子尺寸和化学键的共同作用;考察了Ag+-13X对真实汽油的脱硫性能,结果表明对汽油中的噻吩类硫化物都有脱除效果,为其工业设计提供基础数据。     

Study on Olefin Alkylation of Thiophenic Sulfur in FCC Gasoline Using La2O3-Modified HY Zeolite

HY zeolite modified by La₂O₃ on olefin alkylation of thiophenic sulfur in fluid catalytic cracking (FCC) gasoline was studied in the micro fixed-bed reactor. Reaction pressure 1.5 MPa, reaction temperature 180 °C, WHSV 3.5 h^?1, using HY zeolite modified by 2% La₂O₃, the conversion of thiophene sulfur promoted nearly 10% with good selectivity, comparing with no-modified by La₂O₃. Acidity of modification of HY zeolite with La₂O₃ was tested in Pyridine–IR, it showed that increasing the amount of weak Bronsted (B) acid and the ratio of total B acid with total Lewis (L) acid could strengthen the hydrogen transfer activity of the catalyst, which leaded to improving the capacity of thiophene alkylation. The X-ray diffraction (XRD) results showed that the structure of catalysts could be optimized by loaded proper amount of La₂O₃ for promoting the acidic properties of HY zeolite.     

Vapor Phase Selective Catalytic Oxidation of Cyclohexane over 13X Supported Metal Oxides in the Presence of Ozone

This article reports the application of ozone for the selective oxidation of cyclohexane over 13X molecular sieve supported various metal oxides at ambient temperatures. From the SEM, XRD and HR-TEM results, the impregnated metal oxides are highly dispersed on the support. The activity results reveal that Co/MS, Mo/MS, Cu/MS, and Ag/MS catalysts produce cyclohexanone/cyclohexanol as selective oxidation products, whereas Ce/MS, Mn/MS, and V/MS catalysts yield, predominantly, CO and CO₂. Among them, Co/MS catalyst exhibits better conversion of 12.2% with selectively of 58% to cyclohexanone/cyclohexanol, which is attributed to the simultaneous activation of ozone and cyclohexane (-C-H bond) at ambient conditions.     

Rare earth oxides as carbon oxidation catalysts

The behavior of a number of rare earth oxides as catalysts for the oxidation of graphite in air has been investigated by the methods of thermal analysis. Of the oxides studied, only CeO₂ showed significant activity in accelerating the gasification of graphite by oxygen between 500 and 1000°C. Cerium salts, which decompose to a finely dispersed oxide phase at low temperatures, e.g. Ce (III) nitrate and ammonium Ce (IV) nitrate, were found to be very active catalysts. The catalytic effect may be due to a redox process involving the cyclic conversion of the oxide from the Ce (IV) to the Ce (III) oxidation state, or the oxide particles may provide sites for the dissociative chemisorption of oxygen.     

V-Mo based catalysts for oxidative desulfurization of diesel fuel

Catalytic oxidative desulfurization (ODS) of a Mexican diesel fuel on a spent HDS catalyst, deactivated by metal deposits, was carried out during several reactive-batch cycles in order to study the catalytic performance to obtain low sulfur diesel. To explain catalytic activity results, Mo and/or V oxides supported on alumina pellets were prepared and evaluated in the ODS of a model diesel using tert-butyl hydroperoxide (TBHP) or H₂O₂ as oxidant. The catalytic results show that V-Mo based catalysts are more active during several ODS cycles using TBHP. The performance of the catalysts was discussed in terms of reduced species of vanadium oxide, prevailing on the catalysts, which increase the sulfone yield of refractory HDS compounds (DBT, 4-MDBT and 4,6-DMDBT).     

Cu-ACFS深度脱硫吸附剂的制备与性能

采用浸渍法制备了活性碳纤维(ACFS)负载CuC l的深度脱硫吸附剂Cu-ACFS。在常温常压下,研究了吸附剂对汽油模型溶液中噻吩硫的静态吸附脱硫性能,并优化了吸附剂的制备条件。结果表明,吸附剂的CuC l负载量随浸渍时间的延长刚开始增加很快,到24 h以后趋于平衡,吸附剂的脱硫率随着吸附剂中CuC l负载量的增加而增加,最高可达到89.29%,CuⅠ()在ACFS上的最优负载量为49.596 2 mg/g,对应吸附剂的硫吸附量为11.707 4 mg/g,处理后模型溶液的硫含量由179×10-6降低到30×10-6以下,且吸附剂的再生性能良好。