Among the 8-MR molecular sieves, silicoaluminophosphate SAPO-34 with 3D channels and moderate acid strength represents the most interesting one, the light olefins selectivity of which could reach up to 90% or even higher. [7] The excellent MTO performance of SAPO-34 was first reported by Dalian Institute of Chemical Physics (DICP) in 1990. [8] The researchers also demonstrated the good regeneration stability and high-temperature steam stability of Inspired by these pioneering discoveries, extensive research efforts have been devoted to SAPO-34 focusing on the elucidation of its crystallization mechanism, synthesis optimization, and the relevant catalytic studies, which greatly promote the technological development of the MTO process. Although SAPO-34 exhibits high catalytic activity and high selectivity toward light olefins, it suffers a rapid deactivation due to the coke deposition. Moreover, the MTO reaction on SAPO-34 catalyst is highly exothermal. These features determine that the industrial MTO process based on SAPO-34 catalyst has to adopt fluidized bed reactor, which allows efficient heat transfer and enables the continuous regeneration of the catalyst. In 2010, the world's first commercial MTO unit was successfully commissioned in Baotou, China by DICP (named DMTO technology). [5,10] The production capacity of ethylene and propylene is 0.6 Mt a −1 . To supply commercial catalysts for the DMTO unit, a 2000 t a −1 catalyst manufacturing plant was started up in Dalian in 2008. Afterward, DICP developed the DMTO-II technology, in which the byproducts of C 4 + are separated and introduced into a fluidized-bed cracking reactor to improve the yields of ethylene and propylene. Both the cracking unit and the MTO unit share one regenerator and use the same catalyst. By the end of 2018, thirteen DMTO units have been put into operation with a total production capacity of 7.16 Mt a −1 . Moreover, DICP launched the new generation of DMTO catalyst and completed the pilot test of the DMTO-III technology in 2018, both of which aim to further improve the olefins yield of DMTO units. The catalyst and technology development of the DMTO process are summarized in Figure 1.Based on SAPO-34 catalyst, UOP and Norsk Hydro also developed an MTO process with a low-pressure fast fluidizedbed reactor. [11] In 2013, a commercialized MTO plant (0.3 Mt a −1 olefins) was commissioned in Nanjing, China, which combines the UOP/Hydro MTO process and the total/UOP olefin cracking process to enhance the yield of ethylene and propylene. In addition, Shanghai Research Institute of Petrochemical Technology Methanol conversion to olefins, as an important reaction in C1 chemistry, provides an alternative platform for producing basic chemicals from nonpetroleum resources such as natural gas and coal. Methanol-to-olefin (MTO) catalysis is one of the critical constraints for the process development, determining the reactor design, and the profitability of the process. After the construction and commissioning of the world's first MTO plant by Dalian I...

Mesoporous titanosilicates (MTS-9) are successfully prepared in strong acidic media by a two-step synthesis. MTS-9 has an ordered hexagonal structure and exhibits superior hydrothermal stability and high catalytic activity for the oxidation of the small molecules of phenol and styrene and also of the bulky molecule of trimethylphenol.

Using an organosilane surfactant as the mesopore director, hierarchical porous silicoaluminophosphate SAPO-34 is obtained as an assembly of nanocrystallites intergrown into cubic micrometer-sized crystals, which show excellent performance in MTO reactions with a remarkably prolonged catalyst lifetime and enhanced selectivity of ethylene and propylene compared to the conventional microporous SAPO-34.