Post-synthesis and structural evolution of hollow titanium silicalite-1 with solvent-free method

Generating hollow structure inside titanium silicalite-1(TS-1)is a widely used method to improve its liquid-phase oxidation catalytic performance in industry.However,traditional dissolution-recrystallization method usually required a large amount of aqueous solution of organic template,leading to unfavorable polluted waste,low production efficiency,and high manufacture cost.Here,a facile and environmental friendly strategy was proposed for the post-synthesis of hollow TS-1 zeolite with a solventfree method utilizing NH4HCO3 and tetrapropylammounium bromide as selective etching agents,which reduced the usage of organic template and avoided the liquid waste.The high crystallinity,the microporous structure,and the active Ti sites were preserved at a high product yield(>93%).The formation mechanism of hollow structure was also investigated by exploring effects of different reactants and experimental parameters.Meanwhile,the obtained hollow TS-1 showed an outstanding performance in the epoxidation of 1-hexene in comparison to the parent zeolite.

Landscape Destruction of the Potala Palace Square in Tibet

This paper, with the Potala Palace Square as the object of study, uses the post occupancy method to carry out a field investigation in a joint manner of questionnaire survey, interviews and behavioral trails observation, so as to analyze the landscape destruction behavior of the Potala Palace Square. The results show that the existing problems in design and management of that square as well as the public are responsible for the destruction; male foreign tourists in all ages, who mostly are the unemployed, students and service employees, prove to be destructors. The Potala Palace Square is characterized by regionalism. Opinions on green effect, management and other options of inland public and local residents vary from one to another. Designers and the administrative department of the square are required to come up with countermeasures to avoid the destruction. In practical design, designers must comply with the thinking of "Design Must be for People" and natural ecological principles, and the administrative department should scientifically manage and maintain the square.

A New Synthetic Strategy to Prepare a Polyphosphazene with Charge-Transporting Agents and Nonlinear Optical Chromophores as Side Chains

A new strategy, a post coupling method to develop the polyphosphazene (P2) functionalized with carbazolyl groups and nonlinear optical (NLO) chromophores, has been explored. P2 exhibits good solubility in common organic solvents. The poled film of P2 exhibits a resonant d 33 value of 42 pm/V by second harmonic generation (SHG) measurements.