Orange and semitransparent CBN crystals with maximum crystal-plane of 0. 6 mm in diameter were synthesized under the conditions of 4.5～6.5 GPa, at 1300～1700 ℃ for 4～6 min, by using Mg-Mg_3N_2 as catalyst and adding a little additive.
A new environmentally friendly catalyst, H4SiW12O40-polyaniline (PAn), was prepared, and n-butyraldehyde 1,2-propanediol acetal was synthesized from n-butyraldehyde and 1,2-propanediol in the presence of H4SiW12O40-PAn.
The influence factors of the synthesis were discussed, and the best reaction conditions were found: the molar ratio of n-butyraldehyde to 1,2-propanediol is 1:1.5, the amount of catalyst used is 1.2% of feed stock, and the reaction time is 1.0 h.
H4SiW12O40-PAn is an excellent catalyst for synthesizing n-butyraldehyde 1,2-propanediol acetal, and the yield can reach more than 95.2%.
The partial intermediate products were absorbed on TiO2 surface, which resulted in catalyst deactivation.
But when it was irradiated under UV illumination or solar irradiation for some time, the catalyst could be reused without loss of catalytic activity.