Preparation of Porous Anhydrous MgCl2 Particles by Spray Drying Process

Polyethylene (PE) is indispensable materials in daily lives. The catalyst is necessary to produce PE. Ziegler-Natta catalysts were mostly used to produce PE which consisted of MgCl2/TiCl4 system. Polyethylene particle was reported to replicate the shape of the catalyst particles or catalyst support particles. Therefore, the MgCl2 supports need to satisfy various requirements regarding particle morphology such as shape, particle size with uniform size distribution as well as the porosity. In this research, the preparation of MgCl2 particles from irregular shape of anhydrous MgCl2 by spray drying method was studied. However, because of the hygroscopic properties of anhydrous MgCl2, all steps of experiment in this work were operated under dry N2 atmosphere. The effect of type of alcohol, ethanol, n-propanol and n-butanol as solvent which was used to dissolve MgCl2 before feeding through the spray drying on the particle properties were investigated. The amount of residual alcohol (alcoholic hydroxyl group content), morphology, specific surface area, porosity and crystallinity were determined by GC method, scanning electron microscope (SEM), N2 sorption analyzer and X-ray diffraction (XRD), respectively. The results revealed that spray drying process can produce the porous anhydrous MgCl2 particles which have rough surface, higher porosity and lower crystallinity than original anhydrous MgCl2

NaOH modified WO3/SiO2 catalysts for propylene production from 2-butene and ethylene metathesis

A WO3/SiO2 catalyst is used in industry to produce propylene from 2-butene and ethylene metathesis. Catalysts with various WO3 loading (4% to 10%) were prepared by impregnation and tested for the metathesis of ethene and trans-2-butene. Ion exchange of NaOH onto the WO3/SiO2 catalyst was used to mitigate the acidity of the catalysts in a controlled way. At low WO3 loading, the treatment with large amounts of NaOH resulted in a significant decrease in metathesis activity concomitant with significant W leaching and marked structural changes (XRD, Raman). At higher WO3 loading (6% to 10%), the treatment with NaOH mainly resulted in a decrease in acidity. FT-IR experiments after adsorption of pyridine showed that the Lewis acidic sites were poisoned by sodium. Nevertheless, the metathesis activity remained constant after the NaOH treatment. This suggested that the remaining acidity on the catalyst was enough to ensure the efficient formation of the carbene active sites. Interestingly, Na poisoning resulted in some modification of the selectivity. The mitigation of acidity was shown to favor propene selectivity over the formation of isomerization products (cis-2-butene, 1-butene, etc.). Moreover, treatment with NaOH led to a shorter induction period and reduced coke formation on the WO3/SiO2 catalyst