A series of SAPO⁃34 molecular sieves with different crystallization time were synthesized by hydrothermal method using pseudo⁃boehmite, silica sol and phosphoric acid as raw materials, TEA & TEABr as template. The crystal structure and physicochemical properties of the synthesized SAPO⁃34 molecular sieve were characterized by XRD, SEM and NH3⁃TPD. The catalytic activity of MTO was evaluated in a fixed bed reactor. The results showed that pure phase lamellar SAPO⁃34 molecular sieves were synthesized under different crystallization time. The longer the crystallization time was, the higher the crystallinity was, the greater the lamellar thickness was, and the more the acid centers were. At 450 ℃, 2 h-1, 0.2 MPa, crystallization time 72 h, the SAPO⁃34 molecular sieve had the best MTO catalytic activity with a single⁃pass lifetime 360 min and yield of diene 86.8%.

The aluminum source is made of Al2(SO4)3 solution, and the precipitant is made of NH4HCO3 solution. By modifying the aging step in the preparation process, the structure of the precursor aluminum ammonium carbonate (AACH) and the calcined γ⁃Al2O3 are modulated, and a high specific surface area nano γ⁃Al2O3 with a hierarchical pore structure was prepared. PtSnK/γ⁃Al2O3 long chain alkane dehydrogenation catalyst was prepared with macro⁃mesostructured hierarchical γ⁃Al2O3 as the carrier. C10―C13 long chain alkanes were used as raw materials to evaluate the activity and stability of the catalyst in a small fixed bed reactor. The results of the study indicated that the γ⁃Al2O3 support obtained after secondary modulation had a macro⁃mesostructured hierarchical pore structure, and the pore size distributions of mesopores and macropores were relatively concentrated. The average pore diameter, pore volume, and specific surface area were 25.40 nm, 2.09 cm3/g, and 284.5 m2/g, respectively. The initial conversion of long⁃chain alkanes dehydrogenation over PtSnK/γ⁃Al2O3 catalyst has reached 26.9% under accelerant condition and after 18 hours can still achieve 21.3%, the dehydrogenation conversion rate is higher than that of commercial alumina.

The porous SAPO-11 molecular sieves were prepared by dry-gel method under the condition of single or simultaneous addition of cetyltrimethylammonium bromide (CTAB) and polyethylene glycol (PEG), respectively, with pseudoboehmite, silica sol and phosphoric acid as aluminum source, silicon source and phosphorus source, dipropylamine and diisopropylamine as template. The synthesized SAPO-11 molecular sieves were characterized by XRD, nitrogen physical adsorption and desorption, SEM, NH ₃-TPD and Py-IR. The catalytic performance of the prepared Pt/SAPO-11 molecular sieve in n-dodecane isomerization reaction was investigated on a fixed bed. The results show that the addition of CTAB and PEG in the dry gel synthesis of SAPO-11 can promote the formation of mesoporous structure in the molecular sieve and change its morphology and acid strength. The selectivity and yield of the synthesized multistage pore SAPO-11 catalyst for n-dodecane hydroisomerization are significantly superior to those of the microporous SAPO-11 molecular sieve. The selectivity and yield of isoparaffin of Hier-Sapo-11-cp molecular sieve reach 71.2% and 62.1% respectively at 340 ℃.