Extraction and Reaction Mechanism of Potassium from Associated Phosphorus and Potassium Ore

Potassium and phosphate were extracted at low temperature by acid hydrolysis process to decompose a new type of associated phosphorus and potassium ore. The main factors affecting the dissolution rate were investigated, such as grinding fineness, the amount of sulfuric acid and fluoride salt, reaction time and temperature, etc. Meanwhile, the effects of various factors on the formation of soluble potassium and phosphate were also discussed. The reaction products and residues were determined by X-ray diffraction（XRD）, scanning electron microscopic（SEM） analysis and other means. The results showed that the dissolution rates of potassium and phosphorus were 70wt% and 93.7wt%, respectively, under the conditions of a grain size of 95.64wt% lessthan 0.074 mm, 9.78 g·g^（-1） sulfuric acid, 0.5 g·g^（-1） ammonium fluoride, 160 ℃ and a reaction time of 2h. The thermodynamic and chemical reaction mechanism was revealed that the primary reaction could be completed spontaneously in a temperature range of 298-433 K. The increase of reaction temperature had an important influence on ion exchange reaction, which was more conducive to the spontaneous process. The research will open up a new way for efficient use of potassium ore resources.

Homogeneous-like Alkyne Selective Hydrogenation Catalyzed by Cationic Nickel Confined in Zeolite

The selective hydrogenation of alkynes to their corresponding alkenes is an important type of organic transformation,which is currently accomplished by modified palladium catalysts.Herein,we report that coordinatively unsaturated Ni(II)sites confined in faujasite zeolite,that is,Ni@Y,can efficiently catalyze the selective hydrogenation of various alkynes in both gas-and liquid phase.Spectroscopic and kinetic analyses explicitly reveal that alkyne hydrogenation over Ni@Y follows the homogeneous associative mechanism instead of the classic heterogeneous Horiuti–Polanyi mechanism.Density functional theory calculations confirm that the preferential adsorption of alkynes on coordinatively unsaturated Ni(II)sites is crucial to initiate dihydrogen activation for the subsequent hydrogenation.Ni@Y represents a true heterogeneous catalyst acting as a homogeneous catalyst and shares the advantages of both heterogeneous and homogeneous catalysis.These findings may shed light on the rational design of robust catalysts and new catalytic routes by linking heterogeneous and homogeneous catalysis.