Combustion of Butyl Carbitol using Supported Palladium Catalysts

Abstract

Palladium catalysts supported on CeO 2, Ce 0.75 Zr 0.25 O 2 , ZrO 2, TiO 2 , Nb 2 O 5 , Al 2 O 3 were studied on the total oxidation of butyl carbitol. Several techniques were used to characterize the samples such as diffuse reflectance spectroscopy (DRS), temperature programmed reduction (TPR), cyclohexane dehydrogenation and CO temperature programmed desorption (TPD). DRS and TPR results revealed the presence of bulk PdO and PdO with strong interaction with the support. The catalytic tests showed the following order for decreasing activity: Pd/Ce 0.75 Zr 0.25 O 2 [ Pd/CeO 2 [ Pd/ TiO 2 [ Pd/Nb 2 O 5 [ Pd/Al 2 O 3 [ Pd/ZrO 2 . However, when the turnover frequency (TOF) was calculated, all the samples had similar values.

Catalytic behavior and reaction routes of MEK oxidation over Pd/ZSM-5 and Pd–Ce/ZSM-5 catalysts

“…This is in a good agreement with the H 2 -TPR and XPS results. During the active phase of VOC oxidation over a Pdsupported catalyst, Pd 2+ has been proposed to catalyze the hydrocarbon oxidation, and Pd 0 to promote the catalytic activity by maintaining a Pd 2+ -Pd 0 cycle during dissociation of VOCs, thus accelerating the reaction rate [33][34][35]. In addition, the catalytic oxidation of VOCs usually involves the participation of surface lattice oxygen species via the Mars-van Krevelen model [36].…”

Comprehensive investigation of Pd/ZSM-5/MCM-48 composite catalysts with enhanced activity and stability for benzene oxidation

“…It is well known that there are many factors, such as the support nature (acidity and textural properties) [5,10,14,52] and the active phase state (valence state and dispersion) [9,55,56], affecting the catalytic activity. On the other hand, CO 2 desorption capability may also be correlated to the catalytic activity although this property is seldom considered.…”

“…Moreover, there are different reports in the literature regarding the effect of the Pd state on hydrocarbons catalytic oxidation [54]. As for the active phase in VOCs oxidation over Pd-supported catalysts, i.e., Pd 0 , Pd 2+ or a mixed Pd 0 /Pd 2+ phase, some investigators propose that the most active phase is the mixture of Pd 0 and Pd 2+ , as Pd 2+ is active in hydrocarbons combustion, and the presence of Pd 0 can also enhance the catalytic activity by providing more active sites for VOCs dissociation [5,10,39,54,55], while others claim that Pd 0 is the most active phase in VOCs catalytic oxidation and its stability is a vital factor for a catalyst [6]. The XPS result shows that the fresh catalyst in this work only contains Pd 0 while the used one has predominant Pd 2+ species, thus, we could expect that both Pd 0 and Pd 2+ are responsible for the oxidation reactions.…”

Synthesis and characterization of Pd/ZSM-5/MCM-48 biporous catalysts with superior activity for benzene oxidation

“…It is widely accepted that the support nature (acidity and textural properties) [11,15,50] and the active phase state (valence state and dispersion) [59][60][61], can affect the catalyst activity. There are different reports in the literature regarding the effect of the Pd state on hydrocarbons catalytic oxidation [57].…”

“…There are different reports in the literature regarding the effect of the Pd state on hydrocarbons catalytic oxidation [57]. With regard to the active phase in VOCs oxidation over Pd-supported catalyst, i.e., Pd 0 , Pd 2+ or their mixture phase, most researchers proposed that Pd 2+ is active in hydrocarbon oxidation, and the presence of Pd 0 can promote the catalytic activity by providing more active sites for VOCs dissociation and allowing the overall reaction to proceed more rapidly [2,51,59,62]. The Mars-van Krevelen model is usually applied to hydrocarbons oxidation over Pd-loaded catalysts [63], which assumes that the reaction occurs when a reactant molecule interacts with an oxygen-rich portion of the catalyst, and a portion of the catalyst surface is alternately reduced (Pd 0 ) and oxidized (PdO x ).…”