Investigation of ZSM-5/MCM-41 Composite Molecular Sieve for Reducing Olefin Content of FCC Gasoline

ZSM-5/MCM-41 composite molecular sieve was prepared by the nano-assembling method.The ZSM-5 molecular sieve,the MCM-41 molecular sieve,the ZSM-5/MCM-41 mechanical mixture and the ZSM-5/MCM-41 composite molecular sieve were characterized by X-ray powder diffractometry,N_2 adsorption isotherms,temperature programmed desorption of ammonia and scanning electron microscopy and their properties were analyzed.Using FCC gasoline as the feed,activities of different molecular sieves for reducing olefin content were investigated in a continuous high-pressure micro-reactor unit under the following conditions:a reaction temperature of 400℃,a reaction time of 2 h,a weight hourly space velocity of 3h^(-1),and a reaction pressure of 2.0 MPa.The results showed that the HMCM-41 molecular sieve had low reaction performance,and the HZSM-5 molecular sieve demonstrated high aromatization activity,while the ZSM-5/MCM- 41 composite molecular sieve exhibited a best olefin-reducing performance because of its high isomerization activity and moderate aromatization activity.With a largest olefin-reducmg capability and a reasonable distribution of products,the composite molecular sieve was more suitable for FCC gasoline upgrading compared to other three catalysts.

Synthesis of Mesoporous Molecular Sieve MCM-41 in Extremely Dense System

Mesoporous molecular sieve MCM-41 has been synthesized in the extremely dense system (with H2O/Si<10) and characterized by XRD, N-2 adsorption isotherm as well as probe reactions of cracking of cumene and isomerization of o-xylene.

ON SIMULTANEOUS SUBSTITUTION OF TI AND V INTO MCM-41 TYPE MOLECULAR SIEVE

The new crystalline V-Ti-silicalite with mesoporous MCM-41 type molecular sieve structure is synthesized hydrothermally; The framework IR spectra associated with ESR, Si-29 MAS NMR, DRS and XPS data shows that V and Ti are simultaneously incorporated into V-TiMCM-41 framework.

MCM-41 Prepared with Ionic Liquid and Cethytrimethylammonium Bromide as Co-templates

The mesoporous molecular sieves MCM-41 were prepared using room tempera-ture ionic liquid （RTIL） synthesized in laboratory and cethytrimethylammonium bromide （CTAB） as compound templates for the first time. They were prepared under low aging temperature and short aging time. Via characterizing by XRD and nitrogen adsorption instrument, MCM-41 synthesized by this new method exhibited good crystal structure and narrow pore distribution. The following pre-paratory conditions was optimal： the molar ratio of RTIL to CTAB was 1.0∶1.0, aging at 80 ℃, for 40 h and calcined at 540 ℃. It is found that the acidified MCM-41 improves its activity as catalyst over the unmodified ones.

Large Pore Mesoporous MCM-41 Templated from Cetyltriethylammonium Bromide

Following hydrothermal synthesis process, MCM-41 was synthesized by using cetyltriethylammonium bromide as templating agent. The experimental results showed that MCM-41 with pore diameter in the range of 4-7 nm can be obtained by adjusting nsurf/nsi. It was proved that cetyltriethylammonium bromide is an effective templating agent for increasing pore diameter of molecular sieve MCM-41.

Development of a pentaethylenehexamine-modified solid support adsorbent for CO_2 capture from model flue gas

A novel solid support adsorbent for CO2capture was developed by loading pentaethylenehexamine(PEHA)on commercially available mesoporous molecular sieve MCM-41 using wet impregnation method.MCM-41 samples before and after PEHA loading were characterized by X-ray powder diffraction,N2adsorption/desorption,thermal gravimetric analysis and scanning electron microscope to investigate the textural and thermo-physical properties.CO2adsorption performance was evaluated in a fixed bed adsorption system.Results indicated that the structure of MCM-41 was preserved after loading PEHA.Surface area and total pore volume of PEHA loaded MCM-41 decreased with the increase of loading.The working adsorption capacity of CO2could be significantly improved at 60%of PEHA loading and 75°C.The effect of the height of adsorbent bed was investigated and the best working adsorption capacity for MCM-41-PEHA-60 reached 165 mg·(g adsorbent)-1at 75°C.Adsorption/desorption circle showed that the CO2working adsorption capacity of MCM-41-PEHA kept stable.