Method and system for preparing propylene through chemical-looping oxidative dehydrogenation of propane

Abstract

The invention relates to a method and system for preparing propylene through chemical-looping oxidative dehydrogenation of propane. The method comprises the following steps: reacting propane with oxygen carrier particles in a dehydrogenation reactor to produce propylene, water vapor and Cox gas, wherein the oxygen carrier particles lose oxygen; separating propylene from a gas mixture obtained in the previous step; and subjecting the oxygen carrier particles having lost oxygen and oxygen-containing gas to an oxidation reaction to produce oxygen-poor gas and regenerated oxygen carrier particles,and circulating the regenerated oxygen carrier particles for participation in dehydrogenation. The system comprises a dehydrogenation reactor, a gas mixture purifying device, a gas mixture separatingdevice and an oxidation reactor, wherein the dehydrogenation reactor can receive oxygen carrier particles produced in the oxidation reactor. The method and system for preparing propylene through chemical-looping oxidative dehydrogenation of propane are efficient, energy-saving, environment-friendly, economic and safe.

Description

Technical field [0001] The invention relates to a method and system for preparing propylene by oxidative dehydrogenation of chemical chain propane. Background technique [0002] Propylene is an important basic raw material for chemical synthesis. It occupies an important position in the petrochemical industry. It is mainly used to synthesize other important chemical products such as polypropylene, acrylonitrile and acrylic acid. At present, 80% of the world’s propylene comes from the steam cracking or catalytic cracking (FCC) of naphtha and heavy crude oil, but these two processes mainly produce ethylene and refined oil, and propylene is only a by-product in it. Because of this, the production of propylene is severely restricted. In recent years, with the rapid increase in the consumption of downstream derivatives of propylene, the demand for propylene has continued to rise, and the contradiction between supply and demand has become increasingly obvious. [0003] In order to incr...

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Problems solved by technology

However, these emerging technologies also have some problems. As emerging coal chemical technologies, MTO and MTP need to experience coal / CH 4 -Synthesis gas-methanol-propylene multi-step process, resulting in a more complicated production process, lower product purity and higher equipment investment. In addition, if coal is used as raw material, it will consume a lot of water resources and emit a lot of CO 2 and NOx

DHP is a strong endothermic process, so the process needs to consume a lot of energy, and it needs to be carried out under high temperature and low pressure reaction conditions. Under such conditions, the catalyst is easily deactivated and needs to be regenerated repeatedly, and due to the limitation of thermodynamic equilibrium , the one-way propylene yield is not high (generally less than 30%)

ODHP is to feed oxygen and propane into the reactor at the same time in the presence of a catalyst to make propane react with oxygen to generate propylene and water. Although this technology can be carried out under milder conditions, it can also overcome the thermodynamics in the dehydrogenation process. Balance limit, but propane is prone to over-oxidation reaction in the presence of oxygen to generate COx gas (carbon monoxide and carbon dioxide), which will reduce the yield of propylene, and the use of oxygen will also increase the operating cost, which is not conducive to the safe operation of the equipment. In addition, the The technology also requires expensive air separation plants to ensure a constant supply of oxygen

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