CN-121972189-A - Propane dehydrogenation catalyst and preparation method and application thereof

CN121972189ACN 121972189 ACN121972189 ACN 121972189ACN-121972189-A

Abstract

The invention relates to a propane dehydrogenation catalyst which comprises a composite carrier of formed alumina-silicon carbide, a platinum component and a rare earth component, wherein the platinum component and the rare earth component are loaded on the composite carrier, the composite carrier consists of 60-90 wt% of alumina and 10-40 wt% of silicon carbide, and based on the total mass of the catalyst, the mass fraction of platinum is 0.05-0.30 wt% and the mass fraction of rare earth element oxide is 0.20-3.0 wt%. Meanwhile, the invention also discloses a preparation method and application of the catalyst. The catalyst provided by the invention can be used for producing low-carbon olefin mainly containing propylene in industrial devices such as fixed beds and moving beds, and has the advantages of high propane conversion rate, high propylene selectivity and long-period stability under the condition of not introducing components such as tin, halogen and the like.

Inventors

ZHANG JING
LI CAN
LI ZELONG
Hu Fangpeng
BAI YANLI
REN ZHIYONG
LIU GUOQI

Assignees

兰州大学

Dates

Publication Date: 20260505
Application Date: 20260402

Claims (10)

1. A propane dehydrogenation catalyst is characterized by comprising a composite carrier of formed alumina-silicon carbide, a platinum component and a rare earth component, wherein the platinum component and the rare earth component are loaded on the composite carrier, the composite carrier consists of 60-90 wt% of alumina and 10-40 wt% of silicon carbide, and the mass fraction of platinum is 0.05-0.30 wt% and the mass fraction of rare earth element oxide is 0.20-3.0 wt% based on the total mass of the catalyst.
2. A propane dehydrogenation catalyst according to claim 1, characterized in that the rare earth element is one or a combination of yttrium and lanthanum, the sum of mass fractions of yttrium oxide and lanthanum oxide is 0.30-2.0 wt% in terms of oxide, the average content of the rare earth element in an outer layer area of 0.20-0.50 mm from the outer surface is 1.5-5.0 times the average content of the inner area of the catalyst particles, the platinum component is dispersed in the outer layer area of the catalyst particles in a metal state or a metal oxide state, and the average particle diameter of platinum is 1-5 nm.
3. A propane dehydrogenation catalyst according to claim 1, characterized in that the alumina is gamma-Al 2 O 3 .
4. The propane dehydrogenation catalyst according to claim 1, characterized in that the specific surface area of the composite carrier is 80-180 m 2 /g, and the total pore volume is 0.40-0.90 mL/g.
5. The propane dehydrogenation catalyst according to claim 4, wherein the composite carrier is an extruded body, the molded body is one or a combination of a plurality of cylinders, clover or hollow cylinders, and the diameter of the extruded body is 1.0-2.5 mm.
6. The preparation method of the propane dehydrogenation catalyst according to any one of claims 1 to 5, comprising the following steps: s1, preparing a composite carrier: Mixing pseudo bayer powder, silicon carbide powder, a binder and a pore-forming agent according to the mass ratio of 60-90:40-10:3:1, adding 1-4wt% of dilute nitric acid aqueous solution, kneading into plastic slurry with the water content of 45% -50%, extruding the plastic slurry into strips, drying, and roasting for 2-6 hours in an air atmosphere at 700-900 ℃ to obtain the composite carrier of alumina-silicon carbide; S2, rare earth modification: carrying out pore volume impregnation on the composite carrier and an aqueous solution containing rare earth salt at 15-80 ℃, controlling the volume of the impregnation solution to be 60-90% of the total pore volume of the composite carrier, drying at 80-140 ℃ for 2-12 h after impregnating for 0.5-10 h, and roasting for 1-5 h in an air atmosphere at 500-800 ℃ to obtain a rare earth modified composite carrier, wherein the rare earth loading amount is 0.20-3.0 wt% in terms of oxide; S3 platinum loading: And (3) carrying out pore volume impregnation on the rare earth modified composite carrier and a platinum-containing aqueous solution at 15-80 ℃, controlling the volume of the impregnation solution to be 60-90% of the total pore volume of the rare earth modified composite carrier, drying at 80-140 ℃ for 2-12 h after impregnating for 0.5-10 h, and roasting or reducing for 1-5 h in inert gas or hydrogen-containing inert mixed gas at 300-600 ℃ to obtain the platinum-rare earth propane dehydrogenation catalyst of the alumina-silicon carbide composite carrier.
7. The method for preparing a propane dehydrogenation catalyst according to claim 6, wherein the binder in the step S1 is one or two of silica sol, clay and kaolin, and the pore-forming agent is one or more of cellulose, methylcellulose, starch and organic polymers.
8. The method for preparing a propane dehydrogenation catalyst according to claim 6, wherein the rare earth salt in the aqueous solution containing the rare earth salt in the step S2 is yttrium nitrate, lanthanum nitrate or a mixture thereof, and the rare earth loading amount is 0.20-3.0 wt% in terms of oxide.
9. The method for preparing a propane dehydrogenation catalyst according to claim 6, wherein the aqueous solution containing platinum in the step S3 is chloroplatinic acid or platinum nitrate aqueous solution, the loading amount is 0.05-0.30 wt% based on platinum element, and the reducing atmosphere is hydrogen/inert gas mixture with a volume fraction of 1-20%.
10. A propane dehydrogenation catalyst applied to a propylene preparation reaction by propane dehydrogenation is characterized in that the catalyst is pressed, crushed and screened and then is filled in a fixed bed or moving bed reactor, propane or propane/hydrogen mixed gas is introduced under the conditions of 550-630 ℃ and normal pressure to 0.25 MPa for the propane dehydrogenation reaction, the volume space velocity of the propane is 800-4000 h -1 , the single-cycle reaction time is 10-30 h, so that a low-carbon olefin product mainly containing propylene is obtained, when the activity of the catalyst is reduced, the feeding of reaction raw material gas is stopped, air or air/water vapor mixed gas is introduced, the catalyst is roasted for 0.5-3 h at 520-580 ℃ for regeneration, the hydrogen-containing atmosphere is switched for reduction and activation after the regeneration, the propane feeding is recovered, and the reaction and the regeneration steps are repeated, so that the continuous propylene preparation of propane is realized.

Description

Propane dehydrogenation catalyst and preparation method and application thereof Technical Field The invention relates to the technical field of petrochemical catalytic materials, in particular to a propane dehydrogenation catalyst and a preparation method and application thereof. Background The low-carbon olefin represented by propylene is an important basic raw material for modern petrochemical industry, can be used for preparing various bulk and fine chemical products such as polypropylene, propylene oxide, acetone, acrolein, acrylic acid and esters thereof, acrylonitrile, isopropylbenzene and the like, and has the characteristics of high yield, wide application range, industrial chain length and the like. With the continuous increase of demands for polyolefin materials, high-performance propylene-based monomers and downstream products thereof, propylene consumption has been rising year by year, and the traditional mode of obtaining propylene by relying on steam cracking byproducts and refinery dry gas byproducts has been difficult to meet the demands of newly-built and expanded devices in terms of resource utilization and cost control, and development of propylene preparation routes with special propylene production, relatively simple flow and higher energy efficiency has been urgently needed. The process for preparing propylene (Propane Dehydrogenation, PDH) by propane dehydrogenation takes propane as a raw material, directly produces low-carbon olefin which takes propylene as a main component, has the advantages of short flow, high selectivity, easy enlargement of a device and the like, and is considered as one of the new processes for preparing propylene with stronger competitiveness at present after comprehensively considering factors such as device investment, energy consumption level, environmental friendliness, raw material adaptability and the like. Propane dehydrogenation belongs to a reversible reaction with increased molecular number and strong heat absorption in thermodynamics, and is usually required to be operated at higher temperature and lower pressure in order to drive the reaction to the dehydrogenation direction, but C-C bonds are easier to break under high temperature conditions, side reactions such as cracking, aromatization and the like are easy to induce, a large amount of byproducts and carbon deposit are generated, and meanwhile, the partial temperature gradient of a bed layer is large due to uneven heat release and heat absorption of the reaction, so that active metal sintering and rapid deactivation of a catalyst are caused. Therefore, the development of a propane dehydrogenation catalyst which has high activity, high propylene selectivity, good carbon deposit resistance and excellent heat transfer characteristic is a key for realizing stable and efficient operation of the PDH process. The existing industrial catalysts for propane dehydrogenation mainly comprise chromium-based catalysts and platinum-based catalysts, wherein the chromium-based catalysts have the problems of high hexavalent chromium toxicity, high environmental risk and the like, the application of the chromium-based catalysts is more and more strictly limited, and the platinum-based catalysts are important for research and application because the platinum-based catalysts are nontoxic and can be operated under relatively mild conditions. In the prior publication, patent CN101898130B reports a propane dehydrogenation catalyst which takes platinum group metal as a main active component and tin as an auxiliary agent and is loaded on an alumina carrier, the activity and stability of the catalyst are improved by regulating and controlling Pt/Sn interaction, patent CN106588545A discloses a preparation method of the platinum-tin-based propane dehydrogenation catalyst, the reaction performance is improved by introducing auxiliary agents such as carbon into a Pt-Sn system, patent CN109876808A discloses a propane dehydrogenation catalyst which takes platinum as a main active component and indium and fourth-period metal elements as auxiliary agents, and aims to improve the propane conversion rate and propylene selectivity, and in addition, a plurality of platinum-based propane dehydrogenation catalyst formulas which take single alumina carrier as a base and are matched with Sn, ga, in, zn and halogen, alkali metal and other auxiliary agents exist. However, the technical proposal adopts pure alumina carrier, has limited heat conduction performance, easily generates larger temperature gradient on the bed layer, and simultaneously generally relies on Sn and other second metals and halogen auxiliary agents, and has the problems of fast carbon deposition, fast activity attenuation, high corrosion of devices, high environmental protection pressure and the like under high temperature conditions, and has no effective solution for realizing the platinum-based propane dehydrogenation catalyst with high heat transfer efficiency and hi