Facile Preparation of BaClxFy for the Catalytic Dehydrochlorination of 1-Chloro-1,1-Difluoroethane to Vinylidene Fluoride

BaClxFy as well as BaF2 and BaClF catalysts were prepared by solid-state reaction at room temperature with Ba(OH)2 as the precursor and NH4F/NH4Cl as the F and Cl sources. The catalysts were applied for the dehydrochlorination of 1-chloro-1,1-difluoroethane to vinylidene fluoride at 350 °C. The industrial manufacture of vinylidene fluoride (VDF) is carried out at 600–700 °C, whereas the BaClxFy catalysts provided a promising pathway to produce VDF at much lower temperatures. Unfortunately, the selectivity of VDF over BaF2 decreased from 94% to 84% along with the deactivation of the BaF2 catalyst monotonically. In the presence of small amounts of Cl in BaF2, stabilized selectivity was achieved. Over BaCl0.05F0.95, BaCl0.1F0.9 and BaCl0.25F0.75, no decrease in VDF selectivity was observed. Clearly, the presence of small amounts Cl during solid-state preparation inhibited the growth of BaF2 crystalline significantly. Far smaller particles were achieved. The particle size, or more precisely, the crystal size of the barium catalyst played a major role in the catalytic performance. In addition to the crystal growth, the presence of small amounts of Cl during catalyst preparation changed the chemical state of Ba, and therefore the adsorption and activation of the C–Cl bond for HCFC-142b were altered.

Synthesis and Characterization of Nanocrystalline M-Mg-O and Carbon-Coated MgO Systems

Two different approaches to modify the structure and reaction ability of nanocrystalline MgO have been discussed. In the first case, a series of two-component x%MOx–MgO systems (M = Fe, Co and Ni, x = 1–45 wt.%) was synthesized via sol–gel technique. Aqueous solution of inorganic salt precursor was used as a hydrolyzing agent. Samples obtained were characterized by number of physicochemical methods (differential thermal analysis, X-ray diffraction analysis, low-temperature adsorption, etc.). It was shown that presence of inorganic salt in magnesium hydroxide matrix shifts the temperature of decomposition of latter towards lower values. Structural and textural characteristics of MgO-based oxide systems were found to be strongly affected by the presence of additive and their concentration. Formation of joint phase was observed in the case of cobalt oxide only. Second way of MgO modification was represented by creating a controlled carbon coating over its surface via decomposition of C4H10 at 400 °C. The obtained x%C/MgO (x = 1–10 wt.%) samples were shown to possess the improved reaction ability in destruction sorption of CF2Cl2 as well as in catalytic dehydrochlorination of 1-chlorobutane in presence of water vapors.

Catalytic dehydrochlorination of 1,2-dichloroethane to produce vinyl chloride over N-doped coconut activated carbon

Pyridinic and pyrrolic nitrogen dopants in the N-AC catalyst can adsorb EDC and increase the activity for EDC dehydrochlorination.