Microporous zeolite-type materials, with crystalline porous structures formed by well-defined channels and cages of molecular dimensions, have been widely employed as heterogeneous catalysts since the early 1960s, due to their wide variety of framework topologies, compositional flexibility and hydrothermal stability. The possible selection of the microporous structure and of the elements located in framework and extraframework positions enables the design of highly selective catalysts with well-defined active sites of acidic, basic or redox character, opening the path to their application in a wide range of catalytic processes. This versatility and high catalytic efficiency is the key factor enabling their use in the activation and conversion of different alkanes, ranging from methane to long chain n-paraffins. Alkanes are highly stable molecules, but their abundance and low cost have been two main driving forces for the development of processes directed to their upgrading over the last 50 years. However, the availability of advanced characterization tools combined with molecular modelling has enabled a more fundamental approach to the activation and conversion of alkanes, with most of the recent research being focused on the functionalization of methane and light alkanes, where their selective transformation at reasonable conversions remains, even nowadays, an important challenge. In this review, we will cover the use of microporous zeolite-type materials as components of mono- and bifunctional catalysts in the catalytic activation and conversion of C1+ alkanes under non-oxidative or oxidative conditions. In each case, the alkane activation will be approached from a fundamental perspective, with the aim of understanding, at the molecular level, the role of the active sites involved in the activation and transformation of the different molecules and the contribution of shape-selective or confinement effects imposed by the microporous structure.

Activation and conversion of alkanes in the confined space of zeolite-type materials

In order to increase the yield of ethylene and propylene in the catalytic pyrolysis of heavy oil, ZSM-5 zeolite was modified by Fe 2 O 3 and TiO 2 via pore volume impregnation. XRD, SEM, and TEM analysis indicated that the structure of the ZSM-5 remained intact after modification, and that the Ti and Fe partially entered the channels of the ZSM-5. Measurement of the number of Bronsted acid sites by n-propylamine temperature-programmed reaction and FTIR measurements showed that the Bronsted acid sites of Ti/ZSM-5 (TiO 2 loaded ZSM-5) and Fe–Ti/ZSM-5 (Fe 2 O 3 and TiO 2 loaded ZSM-5) catalysts increased through the polarization function of Ti 4+ . DRS, XPS, and TPR results showed that the presence of Ti species improved the dispersion of Fe species on the surface of ZSM-5, whereas Fe 2 O 3 promoted the reduction of TiO 2 . After modification by Fe 2 O 3 and TiO 2 , the acidity and reduction properties of Fe–Ti/ZSM-5 improved; such improvement led to a decrease of the apparent activation energy of isopropyl benzene cracking over Fe–Ti/ZSM-5 by about 21 kJ/mol compared with that over ZSM-5. As a result, catalyst Fe–Ti/ZSM-5 showed a better catalytic cracking performance of n-decane and isopropyl benzene than catalysts Ti/ZSM-5, Fe/ZSM-5 (Fe 2 O 3 loaded ZSM-5) or ZSM-5.

Interaction of titanium and iron oxide with ZSM-5 to tune the catalytic cracking of hydrocarbons

Bifunctional catalysis in zeolites possessing both Bronsted and Lewis acid sites offers unique opportunities to tailor shape selectivity and enhance catalyst performance. Here, we examine the impact of framework and extra-framework gallium species on enriched aromatics production in zeolite ZSM-5. In this study we compare three distinct methods of preparing Ga-ZSM-5 and reveal direct (single step) synthesis leads to optimal catalysts compared to post-synthesis methods. Using a combination of state-of-the-art characterization, catalyst testing, and density functional theory calculations, we show that Ga Lewis acid sites strongly favor aromatization. Our findings also suggest Ga(framework) - Ga(extra-framework) pairings, which can only be achieved in materials prepared by direct synthesis, are the most energetically favorable sites for reaction pathways leading to aromatics. Calculated acid site exchange energies between extra-framework Ga at framework sites comprised of either Al or Ga reveal a site-specific preference for stabilizing Lewis acids, which is qualitatively consistent with experimental measurements. These findings indicate the possibility of tailoring Lewis acid siting by the placement of Ga heteroatoms at distinct tetrahedral sites in the zeolite framework, which can have a marked impact on catalyst performance relative to conventional H-ZSM-5.

Ethylene Dehydroaromatization over Ga-ZSM-5 Catalysts: Nature and Role of Gallium Speciation.

The properties and the applications of the main monocyclic aromatic hydrocarbons (benzene, toluene, ethylbenzene, styrene, and the three xylene isomers) and the industrial processes for their manufacture from fossil raw materials are summarized. Potential ways for their production from renewable sources with thermo-catalytic processes are described and discussed in detail. The perspectives of the future industrial organic chemistry in relation to the production of high-octane bio-gasolines and monocyclic aromatic hydrocarbons as renewable chemical intermediates are discussed.

https://www.mdpi.com/1996-1073/14/13/4061/pdf

Production of Gasolines and Monocyclic Aromatic Hydrocarbons: From Fossil Raw Materials to Green Processes

Modified ZSM-5 Zeolite for Conversion of LPG to Aromatics

ZSM-5 zeolites, Ga modified via different methods (in situ hydrothermal synthesis, mechanical mixing, incipient wetness impregnation, solid-state ion exchange, and liquid phase ion exchange), were ...

Ga Substitution during Modification of ZSM-5 and Its Influences on Catalytic Aromatization Performance

The present invention relates to a molecular sieve with MFI structure containing phosphorus and metal components, its anhydrous chemical expression formula (by weight of oxide), is (0-0.3), Na2O (0.5-5.5) Al2O3 (1.3-10) P2O5 (0.7-15) MIxOy (0.01-5) M2MOn (70-97) SiO2, in which MI is one selected from transition metals of Fe, Co and Ni and M2 is any one selected from metals of Zn, Mn, Ga and Sn. Said molecular sieve has the excellent functions of increasing production of low-carbon olefin hydrocarbon and raising aromatic hydrocarbon content in the gasoline, and can be used as shape selective active constituent element and used in the petroleum hydrocarbon catalytic cracking catalyst or adjuvant.

MFI structure molecular sieve containing phosphor and metal component and its use

This invention discloses a modified beta-zeolite, whose chemical formula is (0-03)Na2O (05-10)Al2O3 (13-10)P2O5 (07-15)MxOy (70-97)SiO2, wherein M is selected from Fe, Co, Ni, Cu, Mn, Zn or Sn The modified beta-zeolite can be used as the active component for catalysts and adjuvant

Modified beta zeolite

Pressured hydrothermal activation on phosphorus to stabilize framework Al for better ZSM-5-based cracking catalysts

The invention discloses a method for modifying beta molecular sieves, which is characterized in that sodium beta molecular sieves are exchanged for 0.3 to 1 hour between room temperature and 100 DEG C according to the fact that the weight ratio of the molecular sieves to ammonium salts to H2O is 1:0.1-1:5-10, filtered and impregnated into a phosphorus-containing compound solution and a solution containing transition metal compounds for modification, and dried and roasted, wherein the pH value of an impregnating solution is adjusted to be between 6 and 8. The beta molecular sieves containing phosphorus and transition metals obtained by the modification method have higher specific surface area and relative crystallinity; and when the beta molecular sieves are applied as an active ingredient of a catalyst or an auxiliary agent during catalytic cracking of petroleum hydrocarbon, the olefin selectivity of the beta molecular sieves is further improved, so that more olefin raw materials can be provided for generation of low-carbon olefins by further shape selective cracking of the shape selective molecular sieves.

Modification method of beta-molecular sieve

Popular Tasks used by Researchers

How can I help with your research?

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

We encountered an error while loading the panel. Please try refreshing the page.

Something went wrong

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

Anyone with the link can view this chat. You can switch it back to private anytime.

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Ying Ouyang

Author Tools

Chat about Author