The efficient removal of alkyne impurities for the production of polymer-grade lower olefins remains an important and challenging goal for many industries. We report a strategy to control the pore interior of faujasite (FAU) zeolites by the confinement of isolated open nickel(II) sites in their six-membered rings. Under ambient conditions, Ni@FAU showed remarkable adsorption of alkynes and efficient separations of acetylene/ethylene, propyne/propylene, and butyne/1,3-butadiene mixtures, with unprecedented dynamic separation selectivities of 100, 92, and 83, respectively. In situ neutron diffraction and inelastic neutron scattering revealed that confined nickel(II) sites enabled chemoselective and reversible binding to acetylene through the formation of metastable [Ni(II)(C2H2)3] complexes. Control of the chemistry of pore interiors of easily scalable zeolites has unlocked their potential in challenging industrial separations.

No abstract

The selective scission of chemical bonds is always of great significance in organic chemistry. The cleavage of strong carbon−carbon σ bonds in the unstrained systems remains challenging. Here, we report the selective hydrogenolysis of carbon−carbon σ bonds in primary aliphatic alcohols catalyzed by supported metals under relatively mild conditions. In the case of 1-hexadecanol hydrogenolysis over Ru/TiO 2 as a model reaction system, the selective scission of carbon−carbon bonds over carbon−oxygen bonds is observed, resulting in n-pentadecane as the dominant product with a small quantity of n-hexadecane. Theoretical calculations reveal that the 1hexadecanol hydrogenolysis on flat Ru (0001) undergoes two parallel pathways: i.e. carbon−carbon bond scission to produce n-pentadecane and carbon−oxygen bond scission to produce n-hexadecane. The removal of adsorbed CO on a flat Ru (0001) surface is a crucial step for the 1hexadecanol hydrogenolysis. It contributes to the largest energy barrier in n-pentadecane production and also retards the rate for n-hexadecane production by covering the active Ru (0001) surface. The knowledge presented in this work has significance not just for a fundamental understanding of strong carbon−carbon σ bond scission but also for practical biomass conversion to fuels and chemical feedstocks.

No abstract

No abstract