OSDA-free synthesis of FeZSM-22 zeolite from natural minerals for n-octane hydroisomerization

A seed-directed approach to synthesizing Fe ZSM-22 zeolite without organic structure directing agent(OSDA)was developed by using Fe-rich diatomite as all aluminum and iron sources.The Fe ZSM-22zeolite with optimal crystallinity and purity can be obtained by systematically adjusting feed composition and synthesis conditions.Characterizations show that Fe ZSM-22 zeolite synthesized with OSDA-free owns high crystallinity,obvious thin needle-shaped morphology and high Bronsted/Lewis acid ratio.Significantly,when used for n-octane hydroisomerization reaction,its derived catalyst exhibits the best catalytic performance reflected by the highest selectivity to C_(8)isomers compared to the two reference catalysts prepared based on a Fe-containing and a Fe-free ZSM-22 synthesized through an OSDA-directed route from natural diatomite and conventional chemicals,respectively.This work provides an alternative route to sustainably synthesizing heteroatomic zeolites with high performance.

ZSM-22分子筛合成及其正十二烷烃临氢异构化性能:模板剂和动态晶化的影响

以二乙胺(DEA)或1,6-己二胺(DAH)为模板剂,分别在静态或动态条件下合成具有不同形貌和聚集状态的ZSM-22分子筛,采用XRD、SEM、EDS、TEM、NH3-TPD及N2吸附/脱附表征手段对其进行表征分析。并负载Pt在Al2O3上和ZSM-22机械混合制备双功能催化剂,考察其正十二烷的临氢异构化反应性能。结果表明,模板剂和动态晶化会改变ZSM-22分子筛的形貌及聚集状态,并且会影响其酸性、比表面积和临氢异构活性。其中,以二乙胺为模板剂,静态晶化72h合成的ZSM-22具有最优的催化性能,在310℃反应温度下,正十二烷异构化转化率为66%时,异构十二烷的选择性达到90%。但是,模板剂及动态晶化条件对单支链异构体的产物分布影响较小,异构体产物以支链靠近端位的2-甲基十一烷为主,且随着反应温度升高,2-甲基异构体选择性明显降低。

HZSM-22的粒径调控及Pt/HZSM-22的正十二烷加氢异构催化性能

通过调控合成液中的水含量,采用过饱和溶液法,在静态水热条件下合成了三种不同c轴长度的ZSM-22分子筛,对其进行了X射线衍射、扫描电子显微镜、N2物理吸附、NH3-程序升温脱附和吡啶吸附傅里叶变换红外光谱(Py-FTIR)表征。并以所制备的ZSM-22分子筛为酸性载体,在其上负载0.5%(质量分数)的金属Pt作为加(脱)氢活性位点,制备成Pt/ZSM-22双功能催化剂。以正十二烷为探针分子,进行正构烷烃加氢异构化反应,考察了分子筛合成液中水含量对Pt/ZSM-22催化剂加氢异构化性能的影响。结果表明,随着合成液中水含量减少,ZSM-22分子筛粒径减小。但是当水含量低到一定值时,会有方英石和ZSM-5杂晶生成。当分子筛合成液摩尔组成为SiO_(2)∶Al_(2)O_(3)∶K_(2)O∶DEA∶H_(2)O=1∶0.01∶0.08∶0.29∶28时,获得的HZSM-22在所合成的三种分子筛中拥有最多的中、强Brønsted酸量以及较短的c轴长度,对应的双功能催化剂Pt/HZSM-22表现出最佳催化性能。在320℃时,正十二烷转化率为73.24%,异构烷烃收率为57.92%,异构烷烃选择性为79.09%,尤其是中心位置甲基异构体5-甲基十一烷的选择性达到了17.66%。

Removal of Organochlorine from Model Oil Using Mg-Modified ZSM-5 Zeolite:Dechlorination Performance,Regeneration,and Thermodynamics

Various metal-modified ZSM-5 zeolite adsorbents prepared by the impregnation method were applied to the removal of organic chlorides from model naphtha.The adsorption performance and regeneration stability were investigated by static adsorption experiments.The morphologies,structural features,and physicochemical properties of the adsorbents were characterized by X-ray diffraction,Brunauer-Emmett-Teller analysis,NH3 temperature-programmed desorption,scanning electron microscopy,transmission electron microscopy,and pyridine adsorption infrared spectroscopy.The Mg/ZSM-5 zeolite adsorbent possessed a relatively high specific surface area and good metal dispersion and exhibited the best dechlorination and regeneration performance.The characterization results revealed that introduction of the metal exerted a significant influence on the acidic properties of the catalyst surface.A decrease in the ratio of Brønsted acidic sites to Lewis acidic sites and an increase in the amount of moderately acidic sites were confirmed to be responsible for the excellent adsorption performance of the Mg-modified ZSM-5 zeolite.Furthermore,the Langmuir adsorption isotherm model was applied to study the adsorption equilibrium and thermodynamics of the Mg/ZSM-5 adsorbent under mild conditions.The results revealed that the removal of 1,2-dichloroethane by the Mg/ZSM-5 adsorbent was endothermic,spontaneous,disordered,and primarily involved physical adsorption.

Hydroisomerization performance of platinum supported on ZSM-22/ZSM-23 intergrowth zeolite catalyst

Hydroisomerization catalysts Pt/ZSM-22, Pt/ZSM-23, and Pt/ZSM-22/ZSM-23 were prepared by supporting Pt on ZSM-22, ZSM-23, and intergrowth zeolite ZSM-22/ZSM-23, respectively. The typical physicochemical properties of these catalysts were characterized by X-Ray Diffraction （XRD）, N2 absorption-desorption, Pyridine-Fourier Transform Infrared （Py-FTIR）, Transmission Electron Microscopy （TEM）, X-Ray Fluorescence （XRF）, Scanning Electron Microscopy （SEM） and NH3- Temperature Programmed Desorption （NH3-TPD）, and the performance of these catalysts in n-dodecane hydroisomerization was evaluated in a continuous down-flow fixed bed with a stainless steel tubular reactor. The characterization results indicated that the intergrowth zeolite ZSM-22/ZSM-23 possessed the dual structure of ZSM-22 and ZSM-23, and the catalyst Pt/ZSM-22/ZSM-23 had similar pores and weak acidity to Pt/ZSM-22 and Pt/ZSM-23 catalysts. Moreover, Pt/ZSM-22/ZSM-23 catalyst showed a high selectivity in hydroisomerization of long chain n-alkanes to mono-branched isomers. The evaluation results for n-dodecane hydroisomerization indicated that the activity of Pt/ZSM-22/ZSM-23 was the lowest, while the hydroisomerization selectivity was the highest among the three catalysts. The maximum yield of i-dodecane product was 68.3% over Pt/ZSM-22/ZSM-23 at 320 ℃.

ZSM-22分子筛的形貌控制合成及催化长链正构烷烃制生物航空煤油性能

采用水热或水-溶剂热合成法,通过加入不同添加剂、溶剂和模板剂,合成了短棒状、长针状、花瓣状、粗棒状、椭球状和粗束状等不同晶体或聚集体形貌的ZSM-22分子筛.采用XRD、 SEM、 N_(2)物理吸附、NH_(3)-TPD和Py-IR等方法对不同形貌HZSM-22催化剂的理化性质进行了表征;并以小桐子油加氢脱氧后得到的混合长链正构烷烃为原料,对其加氢裂化/异构化制生物航空煤油性能进行了评价.结果表明,由长度约120 nm的小晶粒聚集而成的椭球状形貌的C-4催化剂具有较大的比表面积和丰富的孔口B酸量.在此基础上,以不同晶体形貌的HZSM-22分子筛为载体,采用等体积浸渍法制备了Pt/ZSM-22催化剂,发现椭球状样品Pt/C-4催化剂具有优异的加氢裂化/异构化性能和稳定性.长链正构生物烷烃转化率达94.21%,生物航空煤油收率高达47.87%,异正比达6.0.

Aromatization over nanosized Ga-containing ZSM-5 zeolites prepared by different methods:Effect of acidity of active Ga species on the catalytic performance

Nanosized Ga-containing ZSM-5 zeolites were prepared via isomorphous substitution and impregnation followed by characterized using various techniques. The catalytic performance of the zeolites for the aromatization of 1-hexene was investigated. The results indicate that isomorphous substitution promotes the incorporation of Ga heteroatoms into the framework along with the formation of extra-framework GaO;species（[GaO;]a） that have stronger interactions with the negative potential of the framework. In addition, based on the Py-IR results and catalytic performance, the [GaO;]aspecies with stronger Lewis acid sites produced a better synergism with moderate Br?nsted acid sites and thus improved the selectivity to aromatic compounds. However, the impregnation results in the formation of Ga;O;phase and small amounts of GaO;species that are mainly located on the external surface（[GaO;];）, which contribute to weaker Lewis acid sites due to weaker interactions with the zeolite framework. During 1-hexene aromatization, the nanosized Ga isomorphously substituted ZSM-5 zeolite samples（Gax-NZ5） exhibited better catalytic performance compared to the impregnated samples, and the highest aromatic yield（i.e.,65.4 wt%） was achieved over the Ga4.2-NZ5 sample, which contained with the highest Ga content.

Adsorption of Benzene and Propylene in Zeolite ZSM-5:Grand Canonical Monte Carlo Simulations

The adsorption behavior of benzene and propylene in zeolite ZSM-5 was studied by Grand Canonical Monte Carlo（GCMC） simulations. It could be found that benzene and propylene molecules showed different adsorption behavior in the zeolite cavities. The loadings of propylene were significantly larger than those of benzene at 100 kPa. From the figures of potential energy distribution, the potential energy of benzene/zeolite was more negative than that of propylene/zeolite, so benzene could be adsorbed more stably than propylene. When the temperature was in- creased from 298 to 443 K at 100 kPa, the loading ofpropylene was reduced from 99 to 82 molecules, whereas that of benzene changed little. When benzene and propylene were adsorbed in zeolite simultaneously, the competitive adsorption of them occurred; therefore, the potential energy distribution could be changed significantly. Besides, the adsorption isotherms of benzene and propylene in ZSM-5 at 298 and 443 K were simulated. The results exhibit that the different factors influenced the molecular adsorption at various temperatures and pressures, leading to the diffe- rent rules for the adsorption of benzene and propylene molecules in the zeolite. At a low pressure, the unfavorable energy of propylene/zeolite and the ＂commensurate freezing＂ phenomenon of benzene would make the loadings of itself higher than those of propylene. When pressure was higher than 5 kPa, the adsorption of benzene in ZSM-5 would nearly reach saturation.

ZSM-22催化乙烯叠合制备液体燃料的研究

来源于炼油厂的干气、液化气以及生物质或CO_(2)转化制得的低碳烯烃经叠合反应可制备清洁的高品质液体燃料。以乙烯为低碳烯烃代表物,分别考察ZSM-22以及经四乙基氢氧化铵(TEAOH)改性处理的ZSM-22-A催化剂对乙烯叠合制备燃料油的作用并同时对反应条件进行考察。结果发现,TEAOH改性具有脱硅扩孔、增多酸量的作用,ZSM-22-A表现出了更高的催化活性。该反应合适的温度为280℃,压力为5 MPa,质量空速为0.15~1.35 h^(-1)(根据油品目标进行选择)。进一步考察了两种催化剂的稳定性,发现ZSM-22在反应280 h后开始出现失活,而ZSM-22-A在反应400 h后仍未失活,具有更高的稳定性,表明利用TEAOH改性ZSM-22对于乙烯叠合制备液体燃料具有良好的应用前景。

Synthesis of ZSM-5 zeolite membranes without organic templates using a varying-concentration technique

Template-free nanosized ZSM-5 seeds with an average size of 15 nm were prepared from a synthesis solution with the composition 12Na2O∶100SiO2∶2Al2O3∶2500H2O. By the use of these seeds, thin ZSM-5 zeolite membranes were prepared on the outer surface of a porous α-alumina tube with a pore size of 2 μm in a gel system by varying-concentration synthesis with organic-free template. The first composition synthesis sol-gel was the same as seeds of molar composition and the second one was 12Na2O∶100SiO2∶2Al2O3∶5000H2O at 180 ℃ for 10 h, respectively. XRD shows that the film consists of well-crystallized ZSM-5 zeolite. SEM investigation indicats that the zeolite films on the supports are defect free and the film thickness is approximately 8 μm. The permeances for H2, N2, CH4 and CO2 are 8.94×10-7, 3.27×10-7, 3.9×10-7, 3.14×10-7 and 0.874×10-7 mol·m2·s-1·Pa-1, respectively. The ideal selectivity of membrane at room temperature for H2/CO2, H2/N2, H2/CH4 are 2.84, 2.73 and 2.29, respectively.

Synthesis of ZSM-22/SAPO-11 composite molecular sieve-based catalysts with small crystallites and superior n-alkane hydroisomerization performance

To improve oil quality,ZSM-22/SAPO-11 composite molecular sieves were synthesized by adding ZSM-22 into a synthetic gel of SAPO-11 for n-decane hydroisomerization.The mass ratios of ZSM-22/(ZSM-22+SAPO-11)in the composite molecular sieves were optimized and the optimal ZSM-22/SAPO-11 composite(ZS-9)was obtained.The electrostatic repulsions between the ZSM-22 precursors and the SAPO-11 crystalline nuclei produced small ZSM-22 and SAPO-11 crystallites in ZS-9,which increased the specific surface area and mesopore volume and thereby exposed more acid sites.In comparison with conventional SAPO-11,ZSM-22 and their mechanical mixture,ZS-9 with smaller crystallites and the optimal medium and strong Brønsted acid centers(MSBAC)content displayed a higher yield of branched C_(10) isomers(81.6%),lower cracking selectivity(11.9%)and excellent stability.The correlation between the i-C_(10) selectivity and the MSBAC density of molecular sieves indicated that the selectivity for branched C_(10) isomers first increased and then decreased with increasing MSBAC density on the molecular sieves,and the maximum selectivity(87.7%)occurred with a density of 9.6×10^(−2)μmol m^(−2).

Synthesis and Characterization of ZSM-5/β Co-Crystalline Zeolite

ZSM-5/β co-crystalline zeolites with different content of ZSM-5 have beensynthesized by adding different amount of ZSM-5 to the synthetic system of β zeolite with NaAlO_2,silica sol as the source of aluminum and silica, respectively, and TEA^+ as the template undercontrolled condition of the synthesis. The ZSM-5/β co-crystalline zeolite was studied by XRD, SEM,BET and NH_3-TPD. The reaction activity of toluene alkylation was investigated with a mixture oftoluene-methanol as the feedstock in a pulse micro-reactor over the ZSM-5/β co-crystalline zeolite.It is found that ZSM-5/β co-crystalline zeolite has two kinds of zeolite structure including ZSM-5and β zeolite, not in the form of a physical mixture. The pore structure of ZSM-5/βco-crystalline zeolites is different from that for β zeolite, ZSM-5 and their physical mixture. Inaddition, the peaks of both high and low temperature desorption of ammonia over the ZSM-5/βco-crystalline zeolite shift 23℃ to lower temperatures and the acid amount of its strong acid is 3%more than the physical mixture. So the ZSM-5/β co-crystalline zeolite produces the highest contentof xylene, which is 10.4% higher than the physical mixture. And the ZSM-5/β co-crystalline zeolitehas better selectivity for toluene alkylation and weaker de-methylation than β zeolite, ZSM-5 andtheir physical mixture.

Effect of Alkali Treatment on the Structure and Catalytic Properties of ZSM-5 Zeolite

Catalytic properties of ZSM-5 zeolite samples pretreated with NaOH solution have been investigated. The samples are characterized by XRD, SEM, chemical analysis, and N2 adsorption. The results indicate that mesopores are created in ZSM-5 crystals under alkali treatment without change the microporous structure and acidic strength of the zeolite, but the crystallinity is greatly decreased under severe treatment. IR indicates that the concentration of silanol is greatly enriched by alkali treatment. The etherification activities of ZSM-5 zeolites are greatly increased by alkali-treatment. The noticeably improved catalytic activity of treated samples is ascribed to the formation of mesopores and greatly enriched silanol group.

Catalytic Desulfurization of n-Butyl-sulfide over HZSM-5 Zeolite in the Presence of a Hydrogen Provider

The catalytic desulfurization of a model organic sulfurous compound n-butyl-sulfide in a fixed bed microreactor is studied in the presence of catalyst and a hydrogen provider. The experimental results show that the appropriate reaction conditions are： a mixed catalyst of HZSM-5 zeolite and Co-Mo/Al2O3-TiO2, a reaction temperature of 300℃, atmosphere pressure, a feed speed of 50 mL/h and a mass hourly space velocity of 3.0 h^-1 A higher catalytic property and desulfurization efficiency of the mixed catalyst of HZSM-5 zeolite and Co-Mo/Al2O3-TiO2 is achieved. The adsorption and desulfurization efficiency of the FCC gasoline from Shenghua Refinery, which is affiliated to China University of Petroleum （East China）, is 53.0 %.

Preparation of Mesoporous ZSM-5 Zeolite under Double Ester Base Long Carbon Chains Organosilane Quaternary Ammonium Salt Template Agent

The pore sizes of traditional zeolites are in the range of0. 3-1. 5 nm,which strongly hinder the diffusion of large reactant and product molecules within the zeolite pores. To compensate for it,we tried to create mesopores in traditional microporous zeolites and retain all advantages of microporous zeolites. Mesoporous Zeolite Socony Mobile-Five( ZSM-5) zeolite was synthesized by a new double ester base long carbon chains organosilane quaternary ammonium salt as the soft template agent in hydrothermal method.The structure of the acquired zeolite crystals was confirmed by fieldemission scanning electron microscopy( FE-SEM), transmission electron microscopy( TEM), nitrogen adsorption-desorption measurements and X-ray diffraction( XRD),which indicated that their structure had the same characteristics as traditional ZSM-5 zeolites. Compared with traditional ZSM-5 zeolite,there were 4 nm and 15 nm mesopores in the crystal. The prepared hierarchical porous ZSM-5 zeolite was expected to be effective catalytic materials for chemical reactions involving large molecules.

Pore Structure and Catalytic Performance of Steam-Dealuminated ZSM-5/Y Composite Zeolites

For investigating the effect of dealumination on the pore structure and catalytic performance, ZSM-5/Y composite zeolites synthesized in situ from NaY gel were dealuminated by steaming at different temperatures. XRD (X-ray diffraction) characterization indicates that the relative crystallinity of the composite zeolites decreases with the increase in Si/Al ratio after steaming. N2 adsorption-desorption suggests that more mesopores are formed while the BET (Brunauer, Emmett and Teller) specific surface area and the micropore specific surface area decrease as the temperature of steaming rises. Daqing heavy oil was used as feedstock to test the catalytic cracking activity of ZSM-5/Y composite zeolites. The experimental results of the catalytic cracking performance reveal that the distribution of products differs due to the different conditions of hydrothermal treatment. Further hydrothermal treatment leads to an increase in the yield of light oil, and a decrease in the yield of gas products and coke.

EPR AND HIGH RESOLUTION SOLID-STATE NMR STUDIES ON Fe^(3+) SUBSTITUTED ZSM-5 ZEOLITE

Fe^(3+) substituted ZSM-5 zeolite was studied using EPR and ^(27)A1,^(29)Si MAS-NMR spectroscopy.The results showed that the synthe- sized sample has the typical ZSM-5 structure with Fe^(3+) ionsincorporated in tetrahedric sites in the zeolite framework and there are some para- magnetic centers in the samples.

Study on Mechanism for Alkylation of Benzene with Propylene over β Zeolite and MCM-22 Zeolite by In-situ IR Spectrometry

为有在沸石和 MCM-22 沸石上的丙烯的苯的完化的反应机制分别地被调查由在原处，实验的红外 spectrometry.Three 类型被执行( 1 )煤气阶段的丙烯的红外系列，苯和 isopropyl 苯被记录( 2 )红外系列上述作为被吸附物质，那与沸石晶片相结合的物质被记录( 3 )反应模式的红外系列是测试结果显示出的 recorded.The 完化

THE EFFECT OF DLSPERSED MoO_3 ON STRUCTURE OF ZEOLITE ZSM-11

The dispersion behavior of MoO_3 on ZSM-11 and effect of dispersed MoO_3 on the fram ework structure of ZSM-11 have been studjed using X-ray diffraction and infrared spectroscopy