Study of properties of Al2O3 and TiO2 supported palladium catalysts in reactions of tetrachloromethane hydrogenation

Abstract

Properties of Al 2 O 3 -and TuO 2 -supported palladium catalysts modifi ed with calcium oxide were studied. Catalyst samples 2% Pd/CaO-TiO 2 and 2% Pd/CaO-Al 2 O 3 were examined by the methods of temperatureprogrammed reduction in a fl ow of hydrogen, temperature-programmed desorption of ammonia and carbon(IV) oxide, and X-ray diffraction analysis.

Hydrodechlorination of CCl4 over carbon-supported palladium–gold catalysts prepared by the reverse “water-in-oil” microemulsion method

“…Fig. 4 shows that irrespective of the kind of carbon support the performance of Pd 100 suffers from rapid deactivation, in line with other reports [7][8][9][10][11][12][13][14][15]33]. Palladium deactivation is paralleled by variations in product distribution.…”

“…However, there are some problems such as the improvement of the stability of Pd catalysts and selectivities to target products, i.e., C 1 -C 5 hydrocarbons, remaining to be met. The main drawback for practical application is rapid deactivation of palladium catalysts during HdCl of CCl 4 reaction, although they show a very high initial catalytic activity [7][8][9][10][11][12][13][14][15]. Therefore, the development of new catalysts with highly selective dechlorinating activity and high stability becomes the strategy for the hydrodechlorination of chlorinated hydrocarbons.…”

Effect of silver on the catalytic hydrodechlorination of tetrachloromethane over silica-supported palladium-silver catalysts

“…The difference in reaction conditions would apparently have a big significance for the course of hydrodechlorination. Similarly, Sainero et al [18,19] testing CCl 4 hydrodechlorination over carbon-supported palladium catalysts in the liquid phase also obtained very high selectivity for chloroform, although a vast majority of reports on the same reaction performed in the gas phase shows a predominant formation of chlorine-free compounds (methane and longer hydrocarbons), [1][2][3][4][5][6][7][8][9]. The difference between the results of batch liquid and continuous gas phase hydrodechlorination operations is therefore very significant and its explanation is behind the scope of this communication.…”

“…hydrocarbons, appears now a more prospective solution. Compared to platinum, palladium catalysts were found more useful in such a transformation [1][2][3][4][5][6][7][8][9], however, as mentioned before, they quickly deactivate on stream.…”

“…Compared to other metals, palladium exhibits extraordinary initial catalytic activity and superior selectivity towards less dangerous and still useful products. The main drawback hampering industrial application of palladium catalysts is their rapid deactivation on stream [1][2][3][4][5][6][7][8][9], also in hydrodechlorination (HdCl) of tetrachloromethane.…”