High rates of catalytic hydrogen combustion with air over $$\hbox {Ti}_{0.97}\hbox {Pd}_{0.03}\hbox {O}_{2-\updelta } $$ Ti 0.97 Pd 0.03 O 2 - δ coated cordierite monolith

Abstract

Ti 0.97 Pd 0.03 O 2−δ was coated on γ-Al 2 O 3-coated honeycomb structured cordierite monolith (AHCM) by solution combustion method using dip-dry-heat process. This is a modified conventional method to coat the catalysts on honeycomb structured cordierite monolith (HCM). Formation of Ti 0.97 Pd 0.03 O 2−δ on AHCM was confirmed by XRD. The XPS spectra of Pd(3d) core level confirmed Pd ion in Ti 0.97 Pd 0.03 O 2−δ is in the form of +2 state. The surface morphology of coated catalyst was unchanged by long time exposure to hydrogen combustion reaction; i.e., H 2 + O 2 recombination reaction which indicated the stability of coating on monolith. Ti 0.97 Pd 0.03 O 2−δ showed high rates of H 2 + O 2 recombination compared to 2 atom% Pd(metal)/ γ-Al 2 O 3 , Ce 0.98 Pd 0.02 O 2−δ , Ce 0.98 Pt 0.02 O 2−δ , Ce 0.73 Zr 0.25 Pd 0.02 O 2−δ , Ti 0.99 Pd 0.01 O 2−δ and Ti 0.98 Pd 0.02 O 2−δ. The activation energy of H 2 + O 2 recombination reaction over Ti 0.97 Pd 0.03 O 2−δ is 7.8 kcal/mol. The rates of reaction over Ti 0.97 Pd 0.03 O 2−δ at 60 • C are in the range between 10 and 20 μmol/g/s. The rate of reaction over Ti 0.97 Pd 0.03 O 2−δ increased with increase in the concentration of H 2. For 50 mL of H 2 , it showed rates of the reaction around 36.45 μmol/g/s at room temperature and 230 μmol/g/s at 60 • C. It was found that the rate of reaction due was lower due to hindering effect by adsorption of other gas molecules on the catalytic site. Finally, we propose a mechanism of hydrogen and oxygen recombination reaction over Ti 0.97 Pd 0.03 O 2−δ .

Photocatalytic dye-degradation activity of nano-crystalline Ti1−xMxO2−δ (M =Ag, Pd, Fe, Ni and x = 0, 0.01) for water pollution abatement

“…4(b) represents the Pd 3d core level spectra of Pd 2+ doped TiO 2 which consists of two peaks centered at 338.0 and 343.7 eV corresponding to Pd 3d 5/2 and Pd 3d 3/2 which confirms that Pd is present in the +2 oxidation state. 44,45 When the powder sample (Pd 2+ doped TiO 2 ) was exposed to UV light, the peaks corresponding to Pd 3d 5/2 and Pd 3d 3/2 asymmetrically broaden, as shown in Fig. 4(c), which indicates that Pd is present in its two chemical states i.e.…”

“…4(a) represents the Ti 2p core level spectra which indicates two peaks centered at 458.8 and 465.0 eV corresponding to Ti 2p 3/2 and Ti 2p 1/2 levels (Ti 4+ ), respectively. 44 Fig. 4(b) represents the Pd 3d core level spectra of Pd 2+ doped TiO 2 which consists of two peaks centered at 338.0 and 343.7 eV corresponding to Pd 3d 5/2 and Pd 3d 3/2 which conrms that Pd is present in the +2 oxidation state.…”

Review of Catalysts, Substrates, and Fabrication Methods in Catalytic Hydrogen Combustion with Further Challenges and Applications

“…Ti-based catalysts were also investigated with high catalytic reactivity from room temperature to 120 °C. 85 The Ti-based catalysts were fabricated by coating on a cordierite monolith to overcome the pressure drop and loss of catalysts. Mn, Co, and Ni were added to catalysts to increase the catalytic activity, Mn shows the highest enhancement.…”

“…The fabrication method of these catalysts is the solution combustion method. Ti-based catalysts were also investigated with high catalytic reactivity from room temperature to 120 °C . The Ti-based catalysts were fabricated by coating on a cordierite monolith to overcome the pressure drop and loss of catalysts.…”