Catalytic reaction of methanol to light olefins/propylene

The MTO process with ethylene and propylene as the target products and the FMTP process with propylene as the target product are developed based on SAPO-34 molecular sieve catalyst. SAPO-34 has suitable proton acidity and pore structure, large specific surface area, good adsorption performance, thermal stability and hydrothermal stability. It shows good catalytic activity and selectivity for methanol to olefins reaction and is suitable for The generation of small molecules of ethylene, propylene and n-alkanes, isomeric hydrocarbons and aromatic hydrocarbons will be strictly limited. When SAPO-34 catalyzes methanol, the selectivity of C2=~C4= reaches more than 90%.
  2. Preparation of light olefins from methyl chloride
According to experiments at Dalian Haixin Chemical R&D Center, under the same reaction conditions, the reaction of halogenated methane to prepare light olefins is similar to the MTO reaction in the reaction induction period, product distribution, carbon pool hydrocarbon species distribution in the catalyst, etc. rules. Using SAPO-34 molecular sieve to catalyze the reaction of CH3Cl and CH3Br to prepare light olefins also has better selectivity and yield than other molecular sieve catalysts.
  3. Ethylene to propylene
  Propylene selectivity depends on the pore size and acidic strength of the molecular sieve. SAPO-34 molecular sieve has high selectivity for propylene, high selectivity for 1-butene and 2-butene, and extremely low selectivity for isobutylene. This situation is due to the fact that the diameter of the 8-membered ring pores of SAPO-34 molecular sieve is close to the molecular dynamic diameter of ethylene, propylene and 1-butene, which is conducive to the diffusion of reactants and product molecules into and out of the pores. The moderately strong protic acidity and the shape selectivity of the pore size for molecules result in the SAPO-34 molecular sieve catalyst having a high yield on propylene.

Cracking reaction of high carbon hydrocarbons

  1. Olefin cracking to produce propylene
When SAPO-34 molecular sieve is used as the catalyst, due to its suitable pore size, it limits the generation of products above C5, and has high selectivity for propylene within an effective time. The propylene yield is higher than other molecular sieve catalysts, and the conversion rate is also higher.
  2. Cracking high-carbon hydrocarbons to produce propylene
SAPO-3 molecular sieve has certain catalytic activity and good shape selectivity for low carbon olefins in the catalytic cracking of hydrocarbon fuels. SAPO-34 has suitable acidity and good shape selectivity. Using SAPO-34 molecular sieve as a catalyst has good cracking activity and high propylene selectivity.

Conversion of alkanes to produce low carbon olefins

 1. Oxidative dehydrogenation of ethane
  2. Propane dehydrogenation
  3. Butane dehydrogenation
  The dehydrogenation reaction needs to be carried out on a higher acidic catalytic center, but it also promotes the cracking reaction. In order to avoid the occurrence of cracking reaction and facilitate the dehydrogenation reaction of alkanes, SAPO-34 is used as a carrier to load metal, which allows the intermediate formed by the metal to take away H from the alkanes and the weakly acidic active center in the carrier to form low-carbon olefins.

Molecular sieve membrane

 1. CO2/CH4 gas selective separation
  Gas membrane separation method refers to the process of separating gas mixtures driven by pressure, relying on the adsorption capacity of each component in the gas on the surface of the polymer or molecular sieve membrane and the difference in dissolution and diffusion within the membrane. The gas membrane separation method for CO2/CH4 separation mainly includes:

(1) Due to the continuous decrease in pressure during oil collection, in order to improve the recovery rate, the enhanced oil recovery technology (EOR) of injecting inert gas (CO2) is adopted. The collected petroleum and hydrocarbon gases contain a large amount of CO2, and the separation and recovery of CO2 are very necessary;

(2) Natural gas contains a large amount of acid gas and water vapor. Removing the acid gas can increase the calorific value of the natural gas and reduce the number of pipelines. corrosion. Since natural gas is generally under high pressure, the membrane separation method can save power;

(3) Biogas generally contains 50%-70% methane gas, and its development is beneficial to reducing the use of fossil fuels.
   2. Purification of H2
   SAPO-34 membrane separates H2/CH4 mainly by utilizing the fast diffusion rate of H2. The molecular size of CH4 is close to the pore size of SAPO-34, and the diffusion capacity is lower than that of H2. The separation selectivity of H2 and CH4 has a maximum value as the temperature changes, and decreases slightly with the increase of raw material pressure and CH4 concentration in the raw material.

NOX treatment

NOX easily causes acid rain and photochemical pollution, and is one of the main components of air pollutants. It mainly comes from automobile exhaust. Cu-SAPO-34 is a NOX reduction catalyst with relatively good application status at present. It has good thermal stability, long service life, and can still maintain good catalytic activity in a large amount of humid atmosphere.

Applications in the field of materials

Zinc oxide is a multifunctional material used mainly in reflective coatings, gas sensors, electronic and optical instruments, and varistors. Using microporous SAPO-34 as the main body, nano-ZnO particles were prepared in smaller chabazite cages through zinc salt impregnation and burning. Since the chabazite cage of SAPO-34 is smaller than the supercage of Y-zeolite and the pores of mesoporous SiO2, the particle size of the obtained ZnO particles is smaller, and the quantum size effect is more obvious.