ZnO modified all-silicon zeolite molecular sieve supported Pt catalyst, preparation method and application

Abstract

The invention discloses a preparation method of a ZnO modified Silicalite-1 zeolite molecular sieve supported Pt catalyst. The preparation method comprises the following steps: immersing a Silicalite-1 Zeolite molecular sieve in a zinc salt aqueous solution, and performing drying and roasting to obtain a ZnO / Silicalite-1 support; immersing the ZnO / Silicalite-1 support in a chloroplatinic acid or ammonium chloroplatinate aqueous solution, and performing drying and roasting to obtain the ZnO modified Silicalite-1zeolite molecular sieve supported Pt catalyst. The reforming catalyst prepared withthe method has an acid center and a metal active center required for aromatization of paraffins, and paraffin can be subjected to dehydrogenation, isomerization, cyclization and other processes for generation of arene under dual-function synergistic action of metal and acid. Pt particles have better sulfur resistance due to strong interaction between the Pt particles and ZnO clusters.

Description

technical field [0001] The invention belongs to the technical field of zeolite molecular sieves, in particular to a ZnO-modified Silicalite-1 zeolite molecular sieve loaded Pt catalyst and a preparation method thereof, which is used to convert paraffins, especially C 6 ~C 8 The reforming reaction of paraffins into aromatics. Background technique [0002] Aromatics are an important basic raw material for the petrochemical industry. Among the total of about eight million known organic compounds, aromatics account for about 30%, among which BTX aromatics (benzene, toluene and xylene) are called primary Basic organic chemical raw material. Aromatics are widely used in the synthetic resin, synthetic fiber and synthetic rubber industries. For example, aromatic hydrocarbons are used as raw materials in the production of important synthetic materials such as polystyrene, phenolic resin, alkyd resin, polyurethane, polyester, polyether, polyamide and styrene-butadiene rubber. In a...

AI Technical Summary

Problems solved by technology

Although Pt-based reforming catalysts are mature and widely used, there are still the following problems: (1) Pt / Al 2 o 3 -Cl and reforming catalysts with added metal components such as Re, Sn, Ir, etc. During the use process, the chlorine on the catalyst is continuously lost, resulting in the decline of the acid catalytic function

ZSM-5 and L-type molecular sieve reforming catalysts that do not require chlorine supplementation have been extensively studied, and some have even been applied in industry, but they still have poor product aromatics selectivity, catalysts are prone to carbon deposition and deactivation, and catalysts are resistant to sulfur Poor performance and other issues

For example, the combination of ZSM-5 molecular sieves and traditional reforming catalytic devices has brought considerable benefits to refineries. For example, Exxon Mobil has developed a multi-stage naphtha reforming process and filled rhenium in the last reforming reactor. Content is after the Re / ZSM-5 molecular sieve of 0.3%, the yield of benzene and toluene in the product has increased by 5% and 3% respectively, and the yield of xylene also increases slightly simultaneously, but because above-mentioned zeolite molecular sieve has stronger acidity center, causing it to still have the following problems when it is used as a reforming catalyst: (1) a large amount of dry gas (C 1 +C 2 ) generation, so the selectivity of aromatics products is relatively poor; (2) carbon deposits are easily generated in the process of catalyst catalyzing the conversion of paraffins into aromatics, resulting in poor stability of the catalyst

However, this type of reforming catalyst still has the following problems: (1) poor catalyst stability, mainly reflected in the agglomeration of noble metal Pt particles and the easy carbon deposition of the catalyst; score less than 10 -7

The above shortcomings severely limit the industrialization process of this type of catalyst

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