Hydrodechlorination of Tetrachloromethane over Palladium Catalysts Supported on Mixed MgF₂-MgO Carriers.
نویسندگان
چکیده
Pd/MgO, Pd/MgF₂ and Pd/MgO-MgF₂ catalysts were investigated in the reaction of CCl₄ hydrodechlorination. All the catalysts deactivated in time on stream, but the degree of deactivation varied from catalyst to catalyst. The MgF₂-supported palladium with relatively large metal particles appeared the best catalyst, characterized by good activity and selectivity to C₂-C₅ hydrocarbons. Investigation of post-reaction catalyst samples allowed to find several details associated with the working state of hydrodechlorination catalysts. The role of support acidity was quite complex. On the one hand, a definite, although not very high Lewis acidity of MgF₂ is beneficial for shaping high activity of palladium catalysts. The MgO-MgF₂ support characterized by stronger Lewis acidity than MgF₂ contributes to very good catalytic activity for a relatively long reaction period (~5 h) but subsequent neutralization of stronger acid centers (by coking) eliminates them from the catalyst. On the other hand, the role of acidity evolution, which takes place when basic supports (like MgO) are chlorided during HdCl reactions, is difficult to assess because different events associated with distribution of chlorided support species, leading to partial or even full blocking of the surface of palladium, which plays the role of active component in HdCl reactions.
منابع مشابه
Improved Pd-on-Au bimetallic nanoparticle catalysts for aqueous-phase trichloroethene hydrodechlorination
Groundwater remediation through the catalytic breakdown of the undesired contaminants is a more effective and desirable approach than the conventional physical displacement methods of air-stripping and carbon adsorption. Palladium-on-gold nanoparticles (Pd/Au NPs) have recently been shown to catalyze the hydrodechlorination of trichloroethene in water, at room temperature, and in the presence o...
متن کاملCatalytic Hydrodechlorination of trichloroethylene by Anion Exchange Resin Supported Palladium Catalysts by
................................................................................................................................. ii ACKNOWLEDGEMENTS ........................................................................................................ iii LIST OF TABLES ....................................................................................................................... vi ...
متن کاملReactivity of Aryl Halides for Reductive Dehalogenation in (Sea)water Using Polymer-Supported Terpyridine Palladium Catalyst.
A polymer-supported terpyridine palladium complex was prepared. The complex was found to promote hydrodechlorination of aryl chlorides with potassium formate in seawater. Generally, reductive cleavage of aryl chlorides using transition metal catalysts is more difficult than that of aryl bromides and iodides (reactivity: I > Br > Cl); however, the results obtained did not follow the general tren...
متن کاملExceptionally efficient catalytic hydrodechlorination of persistent organic pollutants: application of new sterically shielded palladium carbene complexes.
A new sterically shielded carbene with branched aromatic substituents (9a) and two palladium halogenide complexes (11a,b) have been prepared. The single crystal X-ray structures of free carbene 9a and palladium carbene complexes 10b and 11a were determined. Very high catalytic efficiencies were evident for the sterically shielded palladium carbene complexes 10b and 11a,b when the latter complex...
متن کاملCarbon Nanotubes Synthesis by Chemical Vapor Deposition of Methane over Zn – Fe Mixed Catalysts Supported on Alumina
Carbon nanotubes were synthesized over a series of Zn-containing Fe/alumina catalysts by chemical vapor deposition method at two reaction temperatures of 850 and 950 °C using methane as a carbon source. Catalysts were synthesized by keeping Fe concentration constant and varying Zn concentration to study the effects of Zn. The catalysts were characterized using X – ray powder diffraction and N2 ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Molecules
دوره 21 12 شماره
صفحات -
تاریخ انتشار 2016