Direct synthesis of shaped MgAPO-11 molecular sieves and the catalytic performance in n -dodecane hydroisomerization.

In industrial application, molecular sieves are usually used in a certain shape. This requires the addition of binder and causes the reduction of both the molecular sieve content and catalytic performance. Herein, pseudo-boemite was mixed with deionized water at room temperature, followed by the drop-wise addition of phosphoric acid, magnesium acetate solution, hydrofluoric acid, di- n -propylamine and 1-ethyl-3-methyl imidazolium bromide with vigorous stirring. The molar ratio of Al 2 O 3  : P 2 O 5  : MgO : HF : DPA : [EMIm]Br : H 2 O in the gel was 1 : 1 : 0.03 : 0.18 : 0.4 : 1 : 45. Then the gel was dried, extruded and directly crystallized to form a shaped MgAPO-11 molecular sieve. X-ray diffraction, scanning electron microscopy, N 2 adsorption, ammonia temperature programmed desorption, pyridine adsorption infrared spectroscopy and nuclear magnetic resonance spectroscopy were used to investigate the physicochemical properties of the samples. X-ray diffraction, scanning electron microscopy and N 2 adsorption tests show that the shaped MgAPO-11 molecular sieve is fully crystallized and possesses hierarchical porosity. Mg is incorporated into the molecular sieve framework and the Pt catalyst supported by the obtained shaped MgAPO-11 exhibits excellent catalytic performance with n -dodecane conversion of 94% and isomer selectivity of 95% at 280 °C. Such a method for the direct synthesis of shaped molecular sieves shows potential for the green synthesis of molecular sieves in industry.