Number Of Acid Sites Research Articles

Green hydrogen production from ammonia water by liquid–plasma cracking on solid acid catalysts

In this study, a method for producing green hydrogen from ammonia water using plasma cracking was proposed. Solid acid catalysts, FAU and MFI zeolites, were used as catalysts. Zeolites were prepared by varying the Si/Al molar ratio to investigate the relationship between the acid sites of the catalyst and the reaction activity. The plasma was directly discharged into the ammonia water to generate hydrogen from the decomposition of ammonia. The gaseous products from the ammonia decomposition by plasma were mostly hydrogen with some nitrogen. No CO2 was produced. Even when the catalyst was not injected, approximately 100 L/h of hydrogen was produced only by plasma discharge. The injection of the FAU or MFI zeolite catalysts improved the hydrogen production rate. The rate of hydrogen production obtained from the decomposition of ammonia water by catalyst and plasma irradiation was the highest for the FAU zeolite with the highest number of acid sites. The hydrogen production rate tended to increase in proportion to the number of acid sites in the catalyst.

New insights into electronic structure effect of the SnMnOx nanorod catalysts for low-temperature catalytic combustion of o-dichlorobenzene.

For the catalytic combustion reaction of chlorinated volatile organic compounds (CVOCs), the electronic structure of the catalyst surface are important factors in determining the activity, selectivity, and chlorine-resistance stability. Herein, a series of SnMnOx catalysts for the catalytic combustion of CVOCs were prepared by the changing of Sn-doping way to regulate the electron valance state of Mn element, including reflux (R-SnMnOx), co-precipitation (C-SnMnOx) and impregnation (I-SnMnOx). It was discovered that the R-SnMnOx catalyst had better activity and chlorine resistance than the R-MnOx, C-SnMnOx and I-SnMnOx catalyst, and the doping ways of Sn in MnOx catalyst could regulate greatly the surface acidity, active oxygen species, the chemical state of Mn&+ species, and redox ability. Especially, the R-SnMnOx catalysts exhibit excellent water resistance, and the reasons were related to the strong interaction of Sn&+ and Mn&+, which could promote obviously the dispersion of active Mn species, form a large number of acid sites, provide the abundant lattice oxygen species, and own the excellent redox ability, which accelerate the rate of charge transfer between Sn&+ and Mn&+ (Sn4++Mn2+→Sn2++Mn4+) to produce the abundant active species and accelerate the rapid conversion of benzene and intermediates conversion.

Al-Doped Core-Shell-Structured Ni@Mesoporous Silica for Highly Selective Hydrodeoxygenation of Lignin-Derived Aldehydes.

Selective deoxygenation of chemicals using non-noble metal-based catalysts poses a significant challenge toward upgrading biomass-derived oxygenates into advanced fuels and fine chemicals. Herein, we report a bifunctional core-shell catalyst (Ni@Al3-mSiO2) consisting of Ni nanoparticles closely encapsulated by the Al-doped mesoporous silica shell that achieves 100% vanillin conversion and >99% yield of 2-methoxy-4-methylphenol under 1 MPa H2 at 130 °C in water. Due to the unique mesoporous core-shell structure, no significant decrease in catalytic activity was observed after 10 recycles. Furthermore, incorporating Al atoms into the silica shell significantly increased the number of acidic sites. Density functional theory calculations reveal the reaction pathway of the vanillin hydrodeoxygenation process and uncover the intrinsic influence of the Al sites. This work not only provides an efficient and cost-effective bifunctional hydrodeoxygenation catalyst but also offers a new synthetic protocol to rationally design promising non-noble metal catalysts for biomass valorization or other widespread applications.

Effect of chlorine on the performance of Cr-K/γ-Al2O3 catalyst for n-hexane dehydrogenation

Dehydrogenation of n-hexane on Cr-K/γ-Al2O3 catalyst can produce n-hexenes and benzene efficiently, while the catalyst deactivates rapidly. This work discovers that introducing an appropriate amount of Cl (NH4Cl) to the Cr-K/γ-Al2O3 catalyst can significantly improve catalytic activity and enhance stability, which is caused by increased proportion of Cr6+ oxides and number of Lewis acid sites, improved dispersion of CrOx and depressed coke deposition. While excessive Cl further increases the acidity of the catalyst, accelerating the side reactions like cracking and isomerization, meanwhile the inactive Cr-Cl species are formed inevitably. Surprisingly, introducing Cl in the form of KCl can effectively avoid these negative influences owing to the strong interaction between Cl and K. For 13 wt%Cr-2.5 wt%KCl/γ-Al2O3 catalyst, 61.2 wt% of n-hexane conversion, 93.1 wt% of selectivity to dehydrogenation products can be achieved, in which the selectivities to n-hexene and benzene are 20.4 wt% and 70.1 wt%, respectively.

Gold/Substituted Hydroxyapatites for Oxidative Esterification: Control of Thin Apatite Layer on Gold Based on Strong Metal-Support Interaction (SMSI) Results in High Activity.

Gold nanoparticles (Au NPs) deposited on various cation- and anion-substituted hydroxyapatites (Au/sHAPs) show oxidative strong metal-support interaction (SMSI), wherein a thin layer of the sHAP covered the surface of the Au NPs by heat treatment in an oxidative atmosphere. Calcination of Au/sHAPs at 300 °C caused a partial SMSI and that at 500 °C gave fully encapsulated Au NPs. We investigated the influence of the substituted ions in sHAP and the degree of the oxidative SMSI on the catalytic performance of Au/sHAPs for oxidative esterification of octanal or 1-octanol with ethanol to obtain ethyl octanoate. The catalytic activity depends on the size of the Au NPs but not on the support used, owing to the similarity of the acid and base properties of sHAPs except for Au/CaFAP. The presence of a large number of acidic sites on CaFAP lowered the product selectivity, but all other sHAPs exhibited similar activity when the Au particle size was almost the same, owing to the similarity of the acid and base properties. Au/sHAPs_O2 with SMSI exhibited higher catalytic activity than Au/sHAPs_H2 without SMSI despite the fact that the number of exposed surface Au atoms was decreased by the SMSI. In addition, the oxidative esterification reaction proceeded even though the Au NPs were fully covered by the sHAP layer when the thickness of the layer was controlled to be less than 1 nm. The substrate can access the surfaces of the Au NPs covered by the thin sHAP layer (<1 nm), and the presence of the sHAP structure in close contact with the Au NPs resulted in significantly higher catalytic activity compared with that for fully exposed Au NPs deposited on the sHAPs. This result suggests that maximizing the contact area between the Au NPs and the sHAP support based on the SMSI enhances the catalytic activity of Au.

Glycerol Conversion into Allyl Alcohol Using a Coke‐tolerant ZnAl2O4‐β Zeolite Catalyst: Effect of Structural, Textural, and Acidic Properties on Catalytic Stability

AbstractCatalysts with different ZnAl2O4 contents impregnated in beta zeolite were synthesized and their catalytic activity in glycerol dehydration to allyl alcohol was investigated. The materials were characterized by XRD, XRF, FTIR, DRIFTS‐ pyridine, NH3‐TPD, and N2 physisorption. In addition, the surface electrostatic potential maps were generated by a molecular mechanics approach. The XRD patterns indicated a high dispersion of the ZnAl2O4, evidenced by the absence of reflections in the diffractograms, except for the sample containing the highest spinel content. The FTIR spectra indicated the presence of zinc aluminate spinel in the zeolite matrix. The DRIFTS‐pyridine and NH3‐TPD analyses indicated that the incorporation of ZnAl2O4 modifies the acidic properties of the zeolite concerning the number, type, and distribution of acid sites. The N2 physisorption tests showed the maintenance of the micro and mesoporous properties of H‐BEA after modification, despite the reduction of the specific area and pore volume values. The samples impregnated with the ZnAl2O4 phase showed larger mesopores sizes, which may favor its catalytic performance. The catalytic tests indicated the allyl alcohol production for the impregnated materials, which the best results were obtained by the sample containing 2 % of ZnAl2O4, with 90.65 % glycerol conversion and 37 % allyl alcohol selectivity due to appropriate tuning of the acidic and textural properties, as well as the presence of basic sites evidenced by CO2‐TPD analysis and electrostatic potential maps. The presence of acid‐base sites is essential to conduct hydrogen transfer, according to the proposed mechanism, generating allyl alcohol. Finally, the results with a longer reaction period showed greater stability for the sample impregnated with low spinel content, whose coke deposition was smaller, which may be related to the larger size of secondary mesopores.

Influence of the structure and acidity of zeolites on the synthesis of solketal from glycerol and acetone

In order to establish the main factors that make it possible to regulate the activity and selectivity of the solketal synthesis process from glycerol and acetone, the acidic and catalytic properties of mordenite (MOR, SiO2 /Al2O3 = 29.2) and faujasite (FAU, SiO2 /Al2O3 = 14.9, 97 and 810) were studied. The reaction was investigated at 25 and 50°C, at acetone/glycerol molar ratio of 2.5. In the presence of zeolites, solketal is the main product with a selectivity of 88.1–94.7 %. It has been shown that the main factors determining the conversion of glycerol and the yield of solketal are the availability of reagents to active sites, the number and strength of acid sites, as well as their resistance to the poisoning effect of water molecules formed during the reaction.

Isolated CuO and medium strong acid on CuO/Nb2O5-H catalyst for efficient enhancement of triethylamine selective catalytic oxidation

The selective catalytic oxidation (SCO) of triethylamine (TEA) to harmless N2, CO2, and H2O is an appropriate elimination technology. It is necessary to develop the catalysts capable of working under mild condition and with excellent N2 selectivity for this reaction. In this article, the CuO/Nb2O5-H catalysts with various loadings were characterized and employed for the SCO of TEA. The 15 %CuO/Nb2O5-H demonstrated the most noticeable catalytic performance. At 220 °C, the conversion of TEA reached 100.0 %, and the selectivity of N2 was 96.0 %. XPS, UV–vis results demonstrated the presence of isolated CuO species in the catalyst and auger electron energy spectra proved the content of Cu2+ species over 85 %. Pyridine-IR and NH3-TPD demonstrated the presence of a substantial number of acidic sites in Nb2O5-H. Based on the in-situ DRIFTs results, the adsorption of TEA on the acidic sites of Nb2O5-H at low temperature is considered as the initial step in the process, followed by C-N bond activation, cleavage, and adsorption of the -NH* intermediates. The -NH* was oxidized to N2 by highly dispersed copper oxide species on the catalyst surface at 220 °C.

Mild Dealumination of H-ZSM-5 Zeolite for Enhanced Conversion of Glucose into 5-Hydroxymethylfurfural in a Biphasic Solvent System

Transformation of lignocellulosic biomass into high-value chemicals is a viable strategy for sustainable development of a bio-based economy. 5-Hydroxymethylfurfural (HMF) is one of potential platform bio-chemicals for the manufacture of various renewable products. In this work, a commercial H-ZSM-5 zeolite was used as a starting material for preparing a series of acid catalysts with bifunctionality for direct dehydration of glucose to HMF in a biphasic water/tetrahydrofuran system. The pristine H-ZSM-5 was mildly dealuminated by refluxing with dilute nitric acid solutions to adjust its acid properties. Although the acid treatment slightly altered the elemental composition, textural properties, and morphology of zeolite, the total acidity and distribution of acid sites were significantly modified. Some non-framework aluminum (Al) oxide clusters were removed from the parent H-ZSM-5 simultaneously with a partial hydrolysis of zeolitic framework. An increased fraction of coordinatively unsaturated framework Al species enhanced the number of Lewis acid sites. Using 0.1 M solution in the treatment provided the suitable catalyst (0.1DeAl.H-ZSM-5), giving a glucose conversion and HMF yield of &gt;99% and 64.7%, respectively, and a good reusability under the optimized reaction conditions. These results show the industrial potential of the proposed method for simple but efficient preparation of H-ZSM-5 catalysts for producing HMF via the catalytic dehydration of glucose.

The Activity and Cyclic Catalysis of Synthesized Iron-Supported Zr/Ti Solid Acid Catalysts in Methyl Benzoate Compounds

The catalytic activity and cyclic catalysis of different methyl benzoates were studied by using a series of Lewis solid acid catalysts. The iron-supported zirconium/titanium solid acid catalysts were characterized using FTIR, SEM, XRD, and BET. The details of catalytic activity and cyclic catalysis verified that the catalyst catalyzed the reactions of 31 benzoic acids with different substituents and methanol. In addition, the mechanism was revealed according to the microstructure, acid strength, and specific surface area of the catalysts, and the yields of methyl benzoates by the GC-MS. Zr ions had significant effects on the catalytic activity of the catalyst. A certain proportion of Fe and Ti ions additionally enhanced the catalytic activity of the catalyst, with the catalyst-specific composition of Fe:Zr: Ti = 2:1: 1 showing optimal catalytic activity. A variety of substituents in the benzene ring, such as the electron-withdrawing group, the electron-donating group, large steric hindrance, and the position of the group on the benzene ring, had regular effects on the catalytic activity of the methyl benzoates. An increase in the catalyst activity occurred owing to the increases in the catalyst surface and the number of acid sites after the Fe ion was added. The catalytic activity remained unchanged after the facile recycling method was performed.

Support Effect of Ga-Based Catalysts in the CO2-Assisted Oxidative Dehydrogenation of Propane

Carbon dioxide (CO2) assisted oxidative dehydrogenation of propane over Ga-modified catalysts is highly sensitive to the identity of support, but the underlying cause of support effects has not been well established. In this article, SSZ-13, SSZ-39, ZSM-5, silica and γ-Al2O3 were used to load Ga species by incipient wet impregnation. The structure, textural properties, acidity of the Ga-based catalysts and the process of CO2-assisted oxidative dehydrogenation of propane were examined by X-ray diffraction (XRD), nitrogen physisorption (N2 physisorption), ammonia temperature-programmed desorption (NH3-TPD), pyridine chemisorbed Fourier transform infrared spectra (Py-FTIR), OH-FTIR and in situ FTIR. Evaluation of the catalytic performance combined with detailed catalyst characterization suggests that their dehydrogenation activity is positively associated with the number of acid sites in middle strength, confirming that the Lewis acid sites generated by Ga cations are the active species in the reaction. Ga/Na-SSZ-39(9) also has feasible acidic strength and a unique channel structure, which is conducive to the dissociative adsorption of propane and desorption of olefins. The Ga/Na-SSZ-39(9) catalysts showed superior olefins selectivity and catalytic stability at 600 ℃ compared to any other catalysts. This approach to quantifying support acid strength, and channel structure and applying it as a key catalytic descriptor of support effects is a useful tool to enable the rational design of next-generation CO2-assisted oxidative dehydrogenation catalysts.

Trimesic acid-functionalized chitosan: A novel and efficient multifunctional organocatalyst for green synthesis of polyhydroquinolines and acridinediones under mild conditions

Trimesic acid-functionalized chitosan (Cs/ECH-TMA) material was prepared through a simple procedure by using inexpensive and commercially available chitosan (Cs), epichlorohydrin (ECH) linker and trimesic acid (TMA). The obtained bio-based Cs/ECH-TMA material was characterized using energy-dispersive X-ray (EDX) and Fourier-transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analysis. The Cs/ECH-TMA material was successfully used, as a multifunctional heterogeneous and sustainable catalyst, for efficient and expeditious synthesis of medicinally important polyhydroquinoline (PHQ) and polyhydroacridinedione (PHA) scaffolds through the Hantzsch condensation in a one-pot reaction. Indeed, the heterogeneous Cs/ECH-TMA material can be considered as a synergistic multifunctional organocatalyst due to the presence of a large number of acidic active sites in its structure as well as hydrophilicity. Both PHQs and PHAs were synthesized in the presence of biodegradable heterogeneous Cs/ECH-TMA catalytic system from their corresponding substrates in EtOH under reflux conditions and high to quantitative yields. The Cs/ECH-TMA catalyst is recyclable and can be reused at least four times without significant loss of its catalytic activity.

Cobalt-/pH-Modified V2O5-MoO3/TiO2 Catalyst with Enhanced Activity for the Low-Temperature Selective Catalytic Reduction Process

Currently, the elimination of gaseous pollutants—particularly nitrogen oxides—has emerged as a significant concern. Among various deNOx technologies, selective catalytic reduction (SCR) has gained prominence as the primary approach for NOx abatement, owing to its superior performance. In this study, novel low-temperature SCR catalysts were developed by regulating the pH value and doping cobalt based on a V2O5-MoO3/TiO2 (VMT) catalyst. The results show an increased SCR performance with 82.8% and 91.1% for catalysts after pH (=10) modification (VMT-10) and (1 wt%) Co/pH (=10) modification (1CoVMT-10), respectively. H2-TPR, NH3-TPD, XPS and DRIFTS confirmed that the pH regulation transformed polymerization V species into isolated V5+=O, thus leading to an increase in the number of acid sites, which enhanced the NH3 and NO2 adsorption capacity. Furthermore, the DRIFTS study indicated that the NH3-SCR reaction over 1CoVMT-10 followed the E–R and L–H mechanism.

In Silico Activation of CO2, NO2, and SO2 with Light Atom Molecules and Stepwise Conversion of CO2 into Methanol and Water

AbstractCO2, NO2, and SO2 can be activated in silico with tailor‐made light atom tripodal ligand systems carrying particular numbers of Lewis acidic and basic sites in specific relative orientations. In the calculated EO2‐adducts (E=C, N, S), considerable E−O bond elongations of 0.1–0.3 Å, decreasing the E=O double bond character, and O−E−O angle alterations, approaching tetrahedral geometry, activate the donor acceptor complexes towards reduction with BH4−. The lone pairs of the P atoms thereby serve as donors towards the central element, C, N, or S, whereas the electron deficient B atoms serve as acceptors. The charge redistribution within the EO2 complex was monitored by a variety of DFT‐derived real‐space bonding indicators (RSBIs) including bond topologies, non‐covalent contact patches, and electron pair basins. For one CO2‐complex, the reduction towards methanol and water was conducted via stepwise addition of H− and H+. The most critical steps are the initial CO2 uptake due to potential quenching of the ligand systems in their active state, increasing the kinetic barrier, and the release of methanol and water from the ligand system due to potential ligand poisoning. Unbeneficial side reactions in the stepwise reduction and protonation have to be considered.

Development and Investigation of Carbon-Mineral Catalyst Based on Natural Clay and Tire Crush for Oxidative Decomposition of Nonionic Surfactants by Hydrogen Peroxide in Wastewater

Samples of a carbon-mineral catalyst based on natural clay and tire crumb for the reaction of oxidative decomposition of nonionic surfactants by hydrogen peroxide in wastewater have been developed and studied. The iron content in the samples varied in the range of 2.3–3.9 wt %. The effect of sample pyrolysis temperature in the range of 350–800°С on characteristics, the number and type of acid sites on the surface, and the ζ (zeta) potential of colloidal systems based on prepared samples was studied. Using model solutions under static and dynamic conditions, the effect of sample pyrolysis temperature on catalytic properties in the reaction of oxidative decomposition of H2O2 and nonionic surfactant (NS) nonoxynols N-9 by hydrogen peroxide was studied. The best result in the oxidation of nonoxynols N-9 with hydrogen peroxide was obtained in the presence of a carbon-mineral catalyst sample calcined at 650°C.

INFLUENCE OF THE PREPARATION METHOD OF BISMUTH-CONTAINING ZEOLITE CATALYSTS ON THEIR ACTIVITY IN STRAIGHT-RUN GASOLINE PROCESSING

New methods of zeolite HZSM-5 modification with bismuth compounds are proposed. The choice of bismuth as a modifying agent is due to the systematisation and generalisation of the available literature data and experimental results of studying the chemistry and synthesis of bismuth compounds of various compositions. Phases in the resulting bismuth-containing zeolite systems were identified by X-ray phase analysis, and the state of bismuth in chemical compounds was determined. The number and strength of acid sites in the original and modified samples were determined by the method of temperature-programmed desorption of ammonia. The catalytic activity of zeolites was studied in the process of hydrogen-free processing of the straight-run gasoline fraction of oil into high-octane gasolines. The effect of modification methods and process temperature on the structural-group hydrocarbon composition, the yield of gaseous and liquid reaction products was studied, and the octane numbers of the resulting gasolines were determined. It is shown that over the bismuth-containing zeolite catalysts, in comparison with unmodified zeolite, the yield of the target product, high-octane gasoline containing a smaller amount of aromatic hydrocarbons, increases, which makes it more environmentally friendly. It has been established that the production of high-octane gasolines that meet modern requirements for motor fuels is possible over modified zeolites within a wider process temperature range. Based on the studies performed, methods for modifying the HZSM-5 zeolite with bismuth are proposed on the basis of the studies performed. The proposed methods make it possible to improve the efficiency of the catalyst in the process of upgrading the straight-run gasoline fraction of oil.

Mixed-ceria reinforced acid functionalized graphene oxide-Nafion electrolyte membrane with enhanced proton conductivity and chemical durability for PEMFCs

Towards the next-gen energy solutions, Nafion, as a state-of-the-art polymer electrolyte to low temperature fuel cell (LTFC) application has been one of the most demanding hydrogen to clean energy conversion device ever achieved. However, the inherent issue of limiting chemical durability and restricted proton conductivity have always been a topic of concern with pure Nafion membranes. To tackle this, we report a mixed-ceria reinforced phosphorylated graphene oxide (sPGO)/Nafion membrane as a potential electrolyte to simultaneously improve the chemical durability and proton conductivity of bare Nafion by utilizing the redox property of ceria nanoparticles and acidic sites of sPGO for accelerated proton transfer. As a progressive method, the single-step phosphorylation of GO introduced short chain branching along with enhanced number of acidic sites in the Nafion matrix whereas incorporation of mixed-ceria nanoparticles improved the chemical durability of the membrane due to its superior radical scavenging property. As a result, mixed-ceria reinforced sPGO/Nafion (Ce-sPGO/NF) electrolyte membrane showed higher proton conductivity (1.2-times) and chemical durability (8.1-times) than bare Nafion. Furthermore, the polymer electrolyte membrane (PEM) was also showcased high enough thermomechanical and electrochemical stability at 80 °C and 100% relative humidity (RH).

Low-temperature highly selective water delignification based on geopolymer materials

Delignification pretreatment is the main source of high cost and high pollution in biomass processing. This paper reports on a simple cheap geopolymers-based highly selective and efficient pretreatment process for delignification under low-temperature water-cooking without discharging black liquor. The geopolymer with a SiO2/Al2O3 ratio of 4.4 showed the largest number of acidic sites and highest catalytic activity. Under mild reaction conditions (mGeopolymer/mFiber = 1/4, 90 min and 90 °C), the delignification rates of woody (eucalyptus) and herbaceous (bagasse) biomass increased by up to 38.90% and 62.20%, respectively. Moreover, the low-alkali black liquor produced by the new water delignification process facilitates subsequent water treatment, eliminating the need for alkali recovery. This study confirms the immense application prospects of geopolymers for the highly selective delignification of most biomass fibre. This study will develop a low-temperature water-cooking process for the delignification of papermaking or biomass processing without wastewater discharge.

Effect of exposed active sites of semi-amorphous Fe-BTC on photocatalytic CO2 cycloaddition reaction under ambient conditions

The capture and efficient use of CO2 is an important issue because CO2 emissions by burning fossil fuels is a primary cause of greenhouse effect. One of the best solutions to this problem is to convert CO2 into valuable organic products through clean technologies. In this work, semi-amorphous material Fe-BTC with highly efficient photocatalytic CO2 cycloaddition reactions was prepared by adopting two strategies: the coordination of Fe ions with H2BDC affected by different solvents and the defect engineering controlled by relatively low temperatures. Combined with FT-IR, SEM, TGA and BET analysis, the two strategies change the properties of Fe-BTC to a certain extent. The NH3-TPD analysis confirmed that the Fe-BTC prepared in different solvents and temperatures had different number of Lewis acid sites, and more Lewis acid sites were beneficial to improve the yield of the reaction. In addition, DFT theoretical calculation also verified that the defective Fe-BTC obtained by relatively low temperature would expose more active sites. Finally, light also played an irreplaceable role in this reaction, as photogenerated charge carriers produced under light excitation could greatly activate CO2 and epoxides, thereby reducing the energy barrier of the reaction. Based on the above photocatalytic experimental results and characterization, the possible mechanism was proposed and explained. This work would provide an economical and effective strategy to obtain more active sites for CO2 cycloaddition reaction under mild conditions.

Efficient-selective-catalytic aromatization of methanol over Zn-HZSM-5/SAPO-34: Action mechanism of Zn

To improve the performance and stability of catalytic methanol aromatization, the Zn-modified HZSM-5/SAPO-34(Zn-ZS) composite molecular sieve was synthesized by hydrothermal synthesis, and the modified composite molecular sieve was characterized using XRD, SEM, N2 isothermal adsorption-desorption, NH3-TPD, and XPS, and the catalysts were evaluated in catalytic methanol aromatization reactions. The results showed that the introduction of in-situ Zn greatly changes the morphology of the molecular sieve, presenting a polycrystalline stacked bloom-like structure, which brings abundant micro-pore channels to the molecular sieve, but at the same time, the introduction of metallic Zn also will cause more meso-pore channels losses. The introduction of secondary external Zn brought a large number of weak strong acidic sites, and the amount of molecular sieve acid was nearly doubled; weak acidic sites were strengthened, and the ratio of weak to strong acid amount became smaller. The BTX selectivity of the Zn-doped molecular sieve was significantly enhanced and the anti-coking performance was improved. The composite molecular sieve doped with 2% Zn achieves a 41% selectivity for the BTX within the 47 h lifetime, showing good reaction stability.