Aromatization of FCC Gasoline Over Modified HZSM-5 Catalyst

Abstract

Zinc and phosphorus incorporated HZSM-5 catalyst was prepared by adopting incipient wet co-impregnation (Zn-P/HZSM-5). Zn-P/HZSM-5 catalyst exhibited the lowest acidity but the highest aromatization activity with stable performance in the studied period of 16 hr. The process conditions on aromatization reaction and the coke deactivation mechanism of Zn-P/HZSM-5 catalyst were studied on a small-scale, fixed bed reactor using FCC naphtha (75–120°C). The weight contents of ZnO and P₂O₅ were 2% and 4%, respectively. Results showed that Zn-P/HZSM-5 catalyst under a temperature of 450°C, liquid hourly space velocity of 1.0 h^?1, and pressure of 0.1 MPa, the conversions of olefins and alkanes are 96.77% and 88.94%, respectively, the contents of olefins, aromatics in liquid product are 6.79% and 74.57%, respectively. Carbon deposition was the major reason for catalyst deactivation due to the catalyst's good performance as a fresh catalyst after regeneration. All of the blending products fitted the standards of Chinese gasoline.     

Influence of ZnO and P2O5 Content on Modified HZSM-5 on Aromatization of FCC Gasoline

Catalytic properties of different content of ZnO and P₂O₅ supported on HZSM-5 zeolites were studied in the conversion of FCC gasoline (75°C-120°C) into aromatic hydrocarbons with a temperature of 430°C, a liquid hourly space velocity of 1.0 hr^-1, and a pressure of 0.1 MPa. In the reaction, when the contents of ZnO and P₂O₅ are 2% and 4%, respectively, Zn-P/HZSM-5 showed the highest selectivity and activity to aromatic hydrocarbons and conversion of olefins. The content of aromatics in the liquid product and the yield of aromatics reached as high as 94.53%, 68.87%, and 51.74%, respectively.     

The Aromatization of Different FCC Naphtha Fractions over a P-Zn/HZSM-5 Catalyst

Abstract

The aromatization reaction performance of P-Zn/HZSM-5 catalyst was investigated on a fixed bed reactor using five fluid catalytic cracked (FCC) gasoline fractions (<100°C, 50°C–100°C, <120°C, 75°C–120°C, and full fraction) as feedstock, and the effect of feedstock on aromatization is discussed. The results showed that the activity and stability of P-Zn/HZSM-5 catalyst for the aromatization of the 50°C–100°C fraction were high in definite reaction conditions. After 16 hr, the content of olefin and aromatics in liquid product were 5.23 and 79.9%, respectively. The liquid product of low olefin and high aromatics was obtained. The distribution of benzene, toluene, and xylene in liquid product of 50°C–100°C fraction was investigated during aromatization, and the result showed that the toluene content was maximum among the three aromatics contents, the benzene content was minimum at the beginning of the reaction, xylene content became maximum, and benzene was still minimum after reacting for 20 hr. The content of C₉ ⁺ aromatics increased at the first stage of the reaction and then decreased with the increasing reaction time.     

Aromatization of Cyclopentane Over ZSM-5 Catalysts: A Proposal of Reaction Pathway

Abstract

The conversion of cyclopentane over HZSM-5 and GaZSM-5 was studied at 500–600°C in a fixed bed flow reactor. The reaction over HZSM-5 showed that cyclopentane was first cracked to liquified petroleum gas (LPG) that consecutively aromatized to BTX and C₉₊ aromatics. While over GaZSM-5, cyclopentane preferred to oligomerize to larger intermediate namely cyclic hydrocarbon pool that could be converted to C₉₊ aromatics and then cracked to benzene toluene and xylene and LPG. The higher activity was obtained by lowering Si/Al ratio of the parent HZSM-5 and increasing reaction temperature.     

A Study on Modified HZSM-5 Aromatization for FCC Light Gasoline

Abstract

In this article, the HZSM-5 type zeolite catalysts modified with zinc nitrate and calcium nitrate are prepared by impregnation method. The FCC gasoline (<75°C fraction) is observed and studied on the modified HZSM-5 type zeolite catalysts. The results are that the Z _x -HZSM-5 type zeolite catalysts have a high initial aromatic yield but a rapid deactivation. The C _y -HZSM-5 type zeolite catalysts have a lower aromatic yield and a familiar deactivation comparing to Z _x -HZSM-5. The HZSM-5 type zeolite catalysts modified with bimetal zinc nitrate and calcium nitrate have a rather low initial aromatic yield but a long catalyst life; among them, the C_3.5Z_2.0HZSM-5 has the best performance. And also, the C_3.5Z_2.0HZSM-5 type zeolite catalyst has demonstrated good regenerated performance. After regenerated three times, the catalyst still has a good stability. The reaction operational conditions are also observed and studied. The results are that the optimal reaction temperature is 450–490°C, the liquid hours space velocity (LHSV) is 1 h^?1 and the reaction pressure is 0.1 MPa.     

DIRECT CATALYTIC CONVERSION OF METHANE TO HIGHER HYDROCARBONS

Abstract

Using a plug-flow reactor we have been able to demonstrate the conversion of pure methane gas to liquid hydrocarbons via the intermediate formation of methanol. The reaction Was carried out at an intermediate pressure (about 20 atm) and moderate temperature (about 400°C). In the first stage of the reactor methane and oxygen react to produce methanol. In the second stage the methanol was converted by HZSM-5 catalyst to a mixture of hydrocarbons. Analysis of the reaction products showed that all of the oxygen Was used in the reaction. Apart from the unconverted methane the product was composed of oxides of carboy water and C₃+ hydrocarbons. Interestingly, among the liquid hydrocarbons, aromatics were found to be the major constituents.     

Study on product distribution and catalytic performance of ZSM-5 in methanol conversion to gasoline-range hydrocarbons (MTHC)

Precise product distribution data is very important for kinetic modeling of chemical reactions and chemical reactor design. In this work, H-ZSM-5 catalyst was hydrothermally synthesized and characterization tests including XRD, XRF, BET, and NH₃-TPD revealed its physicochemical properties. Then, methanol conversion into hydrocarbons over ZSM-5 was investigated with WHSV of 4 h^?1 at reaction temperature 410°C. Product distribution result indicated that C₃-C₅⁺ and C₂⁼-C₄⁼ were the major products in gaseous phase, and in liquid phase xylenes, three methyl benzene and C₁₀⁺ aromatics were the main components. It was also observed that the synthesized ZSM-5 had good performance in the methanol to hydrocarbons process and gave rise to highest activity (100%) during 10 h of operation approximately.     

FCC Gasoline Hydroisomerization Over Pt/HZSM-5 Catalysts

Abstract

Pt/HZSM-5 bifunctional catalyst of fluid catalytic cracking (FCC) gasoline hydroisomerization was prepared. The influence of calcinations and reduction conditions, the metal-incorporation technique, and metal loading on the hydroisomerization of FCC gasoline over the Pt/HZSM-5 bifunctional catalyst was studied. The process opinion catalyst of FCC gasoline hydroisomerization was obtained under the condition of temperature 290–300°C; pressure 1.5–2.5 Mpa; liquid hour space velocity (LHSV) 2.0–3.0 hr^?1; V(H₂)/V(Oil) = 2.0–3.0. The results showed that calcination conditions have a significant influence on ion-exchanged catalysts, as they control the final metal distribution. The reduction conditions and the method used for platinum incorporation were found to be important factors that affected both the activity and selectivity of the catalysts. Pt/HZSM-5 bifunctional catalyst possessed good activity for hydrogenation and isomerization. The olefin hydrocarbons of FCC gasoline were hydrogenated and the stability of FCC gasoline was improved under condition of unchanged octane number.     

The Aromatization Properties of Nano-HZSM-5 Catalyst

Abstract

In this article, the influence of reaction conditions on the aromatization over nano-HZSM-5 zeolite catalyst was investigated. The experimental results showed that nano-HZSM-5 catalyst has the best aromatization properties under the optimal conditions: reaction temperature 430°C, reaction pressure 0.3 MPa, and liquid hourly space velocity 1 h^?1. At the optimal operational conditions, the conversion of olefins in the feedstock was 76.15%. Aromatics yield and the content of olefins, content of aromatics, and content of isoparaffins in liquid product were up to 84.98%, 12.11%, 39.58%, and 35.23%, respectively.     

Conditions for nonhydrodewaxing reaction of hydrocracking tail oil

Hydrocracking tail oil is used in hydrogenation modification in the hydrocracking process and is an ideal material to produce lube-based oil. Through investigating the effect of operation conditions on properties of dewaxing products under atmospheric pressure, the optimum operation conditions are that reaction temperature is 360°C, volume space velocity is 1.0 h^?1, and distillation temperature is 140°C. Under the optimum condition, the yield of liquid products is higher, and the flash point, pour point, and viscosity of white oil are stable and meet the factory product requirements. Especially, properties of alkane and white oil change little when reaction time is 20 h, which indicates that HZSM-5/Al₂O₃ has better stability. When HZSM-5 molecular sieve catalyst was loaded by pseudo-boehmite, HZSM-5/Al₂O₃ catalyst activity and stability improved and became more beneficial to nonhydrodewaxing reaction of hydrocracking tail oil.     

Effect of operating conditions on alkylation of toluene with methanol

P-xylene (PX) is widely used as a raw material of synthesis of terephthalic acid (PTA) and polyester. With the demand of PTA and polyester, PX is demanded eagerly. The process for preparing PX through alkylation of toluene with methanol has been concerned widely. In an experiment HZSM-5/Al₂O₃ catalyst was prepared by loading pseudoboehmites on HZSM-5. The strength of B acid is adjusted, so side reactions can be controlled effectively. The optimum operating conditions are that molar ratio of toluene to methanol is 2.0, reaction temperature is 410°C, carrier gas flow is 7 mL/min, and WHSV is 1.0 h^?1 by investigating the effect of operating conditions on toluene conversion and PX selectivity. Toluene conversion and PX selectivity are up to 46.2% and 68.07%, respectively, under the optimum operating conditions.     

The Conversion of Syngas to Liquid Fuels in a Dual-Bed Single Reactor Process

The effects of HZSM-5 temperature and weight hourly space velocity (WHSV) on conversion of syngas to liquid fuels were investigated in a single reactor process. The temperature of FT catalyst was constant (463 K), whereas the temperature of HZSM-5 varied (523, 573, 623 K). The value of WHSV ranged between 16 and 24 h^?1. HZSM-5 addition suppressed the formation of CH₄ and remarkably enhanced the formation of iso-C₅-C₁₂ paraffins. An increase of HZSM-5 temperature resulted in an enhancement of gaseous hydrocarbons, C₁₈₊ paraffins, and olefins. The optimal HZSM-5 temperature and WHSV were identified as 523 K and 16 h^?1, respectively.     

Reducing Olefins Content of FCC Gasoline Using a NANO-HZSM-5 Catalyst

Abstract

The study of reducing olefins properties on nano-HZSM-5 catalyst was investigated with a continuous fixed reactor using fraction of fluid catalytic cracking gasoline (75N120°C). The experimental results showed that nano-HZSM-5 catalyst has the best reducing olefins properties under the optimal conditions: temperature 430°C, pressure 0.3 MPa, and liquid hourly space velocity 1 h^?1, and the content of olefins in the feed stock decreased to 12.11% and dropped 31 percentage points. The yield of liquid product, the content of aromatics, and the content of isoalkane in liquid product are up to 84.98%, 39.58%, and 35.23% respectively.     

An Investigation on Isobutane Aromatization Over an H-ZSM-5 Catalyst

The H-ZSM-5(SiO₂/Al₂O₃ = 35) catalyst was synthesized hydrothermally using commercial waterglass as the silica source and it was characterized by XRD, BET, SEM, and NH₃-TPD techniques. Isobutane aromatization over the prepared catalyst was studied and the results were compared with those of propane in a fixed-bed reactor. Despite higher conversion of isobutane, the aromatics selectivity was higher for propane with the former exhibited more rapid catalyst deactivation. Furthermore, isobutane aromatization was carried out at 450–550°C. Higher temperature increased aromatics yield as well as deactivation rate.     

RESIDUUM HYDROTREATING APPLICATION OF IH AND QUANTITATIVE CARBON-13 NMR SPECTROSCOPY FOR THE STUDY OF HYDROTREATED PRODUCTS

ABSTRACT

Bai-Hassan reduced crude (350^°C + ) was hydrotreated in fixed bed reactor with commercial Ni-Mo-alumina catalyst. H and quantitative C NMR are used to derive statistical average structure parameters of feedstock and hydrotreated products. The main aromatic hydrocarbons (of type C_ar,H + C_ar,CH₃ + C_ar,n + C_ar,I) of hydrotreated products decreases by temperature, (at mild conditions) particularly at lower space velocity. The severe operating conditions increases the main aromatic hydrocarbons. An approximate inverse correlation is observed between the behaviour of saturated hydrocarbons and the aromatics of type C_ar,H + C_ar,CH₃ + C_ar,n + C_ar,I during hydrotreating process. Higher temperatures show an increase in the percentage of alkyl aromatics of type C_ar,alkFurthermore, the severe operating conditions promotes the formation of the alkyl aromatics with H_α(ArCH₃) while it decreases the alkyl aromatic having H₈ and H₈ The kinetic study of napthenes formation indicates that this reactin is well correlated with a first-order kinetics. The apparent activation energy lpar;E rpar;, enthalpy lpar;? H rpar;and entropy lpar;? s?lpar; of activation are 23.630 KJ mol 18.390 kJ mol ^-1 and -225.95 J mol^-1 k^-1 respectively.     

Zinc-Modified ZSM-5 Nanozeolites Synthesized by the Seed-Induced Method: Interrelation of Their Textural,Acidic, and Catalytic Properties in DME Conversion to Hydrocarbons

The effect of the method of introduction of zinc cations and the zinc content in a nanocrystalline zeolite of the ZSM-5 type on the physicochemical and catalytic properties of the material in DME conversion to a mixture of liquid synthetic hydrocarbons has been studied. Zinc is introduced into the catalysts both during the zeolite synthesis and the ion exchange (Zn _n Al _m NZ5 and ZnNZ5, respectively). The use of nanocrystalline Zn _n Al _m NZ5 zeolites provides the formation of a mixture of liquid hydrocarbons with a high selectivity of no less than 90%; the liquid hydrocarbons contain more than 70% of isoparaffins and a small amount of aromatic compounds. An increase in the zinc loading of the Zn _n Al _m NZ5 zeolite from 0.9 to ~3% leads to an increase in the methanol content in the aqueous phase of the liquid product, an increase in the selectivity for liquid hydrocarbons, and a slight increase in the concentration of aromatic and unsaturated hydrocarbons in the mixture. In the presence of the ZnNZ5/Al₂O₃ catalyst with Zn introduced by ion exchange, the methanol content in the aqueous phase and the aromatics content in the liquid hydrocarbon mixture are significantly higher. The Zn _n Al _m NZ5 nanozeolites are characterized by a more developed external surface, a higher concentration of mesopores, and higher acidity.     

An in situ study of dimethyl ether conversion over HZSM-5/Al2O3 zeolite catalysts by high-temperature diffuse reflectance infrared fourier transform spectroscopy

Isolated and associated OH groups have been in situ identified by high-temperature diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy of the surface of zeolites calcined until complete removal of water. It has been shown that the Brønsted acid sites (BASs) involved in dimethyl ether (DME) conversion on the zeolite surface exhibit two characteristic bands in the DRIFT spectra. It has been found that the composition of DME conversion products on HZSM-5 zeolite catalysts modified with Mg or Rh is temperature-dependent. Ethanol and a small amount of methanol were detected on an Rh-HZSM-5/Al₂O₃ zeolite catalyst at T = 270°C and were not observed on Mg-HZSM-5/Al₂O₃ under the same conditions. Spectral features of ketene were detected in the DRIFT spectra of the surface of Mg-HZSM-5/Al₂O₃ in a stream of DME. The spectrum of Rh-HZSM-5/Al₂O₃ calcined at 200°C exhibited spectral features of ethyl alcohol and bands characterizing a strong Lewis acid site (LAS) capable of hydrogenating ketene to ethyl alcohol. The spectra of the surface of all the zeolite catalysts tested in a DME stream at 320°C contain bands characterizing olefins and alkanes and do not exhibit the spectral features of alcohols and ketene.     

Ni/HZSM-5上裂解汽油选择加氢裂化的研究

在连续流动固定床装置上,探讨了非贵金属Ni/HZSM-5催化剂对裂解汽油选择加氢裂化反应的特征,考察了镍含量、温度、压力、空速及氢烃体积比等参数的影响。随镍含量的增加,裂解汽油中C6+非芳烃转化率先增加后减小,镍含量为2.1%左右较为适宜。工艺条件中温度和压力的影响较大,空速次之,氢烃体积比最小。在380 ℃、3.0 MPa、质量空速1.245 h-1、氢烃体积比1 000的条件下,以镍含量为2.1%的Ni/HZSM-5为催化剂,65 h内裂解汽油中C6+非芳烃组分转化率保持在95%以上,而芳烃转化率仅有13%; 加氢裂化产物中,C2+正构烷烃达80.96%,其中丙烷60.71%,而甲烷和异构烷烃较少。这表明非贵金属Ni/HZSM-5催化剂可高选择性地裂化C6+非芳烃,适用于裂解汽油加氢裂化制备芳烃联产低碳烷烃。     

Conversion of Syngas to LPG and Aromatics Over Commercial Fischer-Tropsch Catalyst and HZSM-5 in a Dual Bed Reactor

The commercial Co-based Fischer-Tropsch catalyst and HZSM-5 were tested in a single reactor process. FT catalyst was evaluated at 463 K, whereas HZSM-5 was evaluated at various temperatures (523, 573, and 623 K). The effect of syngas flow rate, HZSM-5 temperature and loading on liquefied petroleum gas (LPG) and aromatics selectivities were investigated. HZSM-5 addition suppressed the formation of CO₂ and CH₄, and remarkably enhanced the simultaneous formation of LPG and aromatics. The optimal operating conditions were identified as: T_HZM-5 = 623 K, HZSM-5 loading = 2.5 g, and GHSV = 4.8 L_syngas/(g_cat h).     

Production of aviation fuel by bioethanol conversion on zeolite catalysts

The catalytic process of two-stage conversion of ethanol into jet fuel, wherein the second step is the hydrogenation of aromatic hydrocarbons obtained in the first step, has been studied. It has been shown that at 400°C and an ethanol space velocity of LHSV = 2 h^–1, aromatic hydrocarbons are produced, which are hydrogenated on a Pt/C catalyst in an autoclave at 80–100 atm and T = 200–250°C for 1.5 h with a final yield of naphthenic hydrocarbons on a fed ethanol basis of 15–20%.