Different catalyst samples of nickel(II) and copper(II) phthalocyanines supported over bentonite clay (Indian type) were prepared with complex loadings ranging between 0.2 and 2.2 wt.‐%. Catalyst activities were investigated in the bulk polymerization of methyl methacrylate (MMA) at 80°C in the absence and in the presence of sodium bisulfite as a cocatalyst. In all cases, the catalyst efficiency was evaluated in terms of conversion yield (%), polydispersity index (M̄w/M̄n) was determined via GPC analysis in toluene. The stereotacticity was determined from 1H NMR spectra. Optimum polymerization conditions were determined for both catalyst systems. Samples with metal phthalocyanines loadings of 1.8% were the most active ones. The polymers produced have controlled molecular weights, which are nearly proportional to conversion, show narrow molecular weight distributions and syndiotactic‐rich steric structures. Nickel phthalocyanine seemed to have more stereoregulating effect while copper phthalocyanine had a more enhancing effect for the living polymerization process. The microstructure of solid catalysts was investigated by means of scanning electron microscopy and were correlated with activity data.
The catalytic activity of modified natural kaolinite as a solid acid catalyst for dimethyl ether (DME) preparation was investigated by following up the conversion% of methanol and the yield% of DME. Natural kaolinite (KN) was treated chemically with H 2 O 2 (KT) followed by thermal treatment at 500°C (KC) and then mechano-chemically by ball milling with and without CaSO 4 (KB-Ca and KB, respectively). These samples were characterized by XRD, FTIR, SEM, HRTEM, TGA and NH 3 -TPD techniques. The different techniques showed that the chemical treatment of kaolinite with H 2 O 2 resulted in partial exfoliation/delamination of kaolinite, decreased the amount of acidic sites which is accompanied by increasing their strength. Calcination only decreased the acidic strength and slightly enlarged the particle size mostly due to heat effect. Ball milling resulted in multitude randomly-oriented crystals and increased the amount of acidic sites with the same strength of KT sample. CaSO 4 mostly produced ordered monocrystalline kaolinite and created new acidic sites with slightly lower strength relative to KB. The catalytic activity and selectivity depend on the reaction temperature, the space velocity and the strength of acid sites. The most active sample is KB-Ca, which gives 84% DME due to its high amount and strength of acidic sites. The different modification methods resulted in 100% selectivity for DME. ª 2014 Production and hosting by Elsevier B.V. on behalf of Egyptian Petroleum Research Institute.
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