The separation of Pd and CeO₂ on the inner surface of controlled porous glass (CPG, obtained from phase-separated borosilicate glass after extraction) yields long-term stable and highly active methane combustion catalysts. However, the limited availability of the CPG makes such catalysts highly expensive and limits their applicability. In this work, porous silica obtained from acid leached rice husks after calcination (RHS) was used as a sustainable, cheap and broadly available substitute for the above mentioned CPG. RHS-supported Pd-CeO₂ with separated CeO₂ clusters and Pd nanoparticles was fabricated via subsequent impregnation/calcination of molten cerium nitrate and different amounts of palladium nitrate solution. The Pd/CeO₂/RHS catalysts were employed for the catalytic methane combustion in the temperature range of 150–500 °C under methane lean conditions (1000 ppm) in a simulated off-gas consisting of 9.0 vol% O₂, and 5.5 vol% CO₂ balanced with N₂. Additionally, tests with 10.5 vol% H₂O as co-feed were carried out. The results revealed that the RHS-supported catalysts reached the performance of the cost intensive benchmark catalyst based on CPG. The incorporation of Pd-CeO₂ into RHS additionally improved water-resistance compared to solely Pd/CeO₂ lowering the required temperature for methane combustion in presence of 10.5 vol% H₂O to values significantly below 500 °C (T₉₀ = 425 °C).

Fe₂O₃, Co₃O₄ and NiO nanoparticles were prepared via a citrate method and further functionalized with Pd by impregnation. The pure oxides as well as Pd/Fe₂O₃, Pd/Co₃O₄, and Pd/NiO (1, 5 and 10 wt % Pd) were employed for catalytic methane combustion under methane lean (1 vol %)/oxygen rich (18 vol %, balanced with nitrogen) conditions. Already, the pure metal oxides showed a high catalytic activity leading to complete conversion temperature of T₁₀₀ ≤ 500 °C. H₂-TPR (Temperature-programmed reduction) experiments revealed that Pd-functionalized metal oxides exhibited enhanced redox activity compared to the pure oxides leading to improved catalytic combustion activity at lower temperatures. At a loading of 1 wt % Pd, 1Pd/Co₃O₄ (T₁₀₀ = 360 °C) outperforms 1Pd/Fe₂O₃ (T₁₀₀ = 410 °C) as well as 1Pd/NiO (T₁₀₀ = 380 °C). At a loading of 10 wt % Pd, T₁₀₀ could only be slightly reduced in all cases. 1Pd/Co₃O₄ and 1Pd/NiO show reasonable stability over 70 h on stream at T₁₀₀. XPS (X-ray photoelectron spectroscopy) and STEM (Scanning transmission electron microscopy) investigations revealed strong interactions between Pd and NiO as well as Co₃O₄, respectively, leading to dynamic transformations and reoxidation of Pd due to solid state reactions, which leads to the high long-term stability.

Low-temperature hydrogen production from natural gas via steam reforming requires novel processing concepts as well as stable catalysts. A process using zeolite membranes of the type MFI (Mobile FIve) was used to enrich natural gas with liquefied petroleum gas (LPG) alkanes (in particular, propane and n-butane), in order to improve the hydrogen production from this mixture at a reduced temperature. For this purpose, a catalyst precursor based on Rh single-sites (1 mol% Rh) on alumina was transformed in situ to a Rh1/Al₂O₃ catalyst possessing better performance capabilities compared with commercial catalysts. A wet raw natural gas (57.6 vol% CH₄) was fully reformed at 650 °C, with 1 bar absolute pressure over the Rh1/Al₂O₃ at a steam to carbon ratio S/C = 4, yielding 74.7% H₂. However, at 350 °C only 21 vol% H₂ was obtained under these conditions. The second mixture, enriched with LPG, was obtained from the raw gas after the membrane process and contained only 25.2 vol% CH₄. From this second mixture, 47 vol% H₂ was generated at 350 °C after steam reforming over the Rh1/Al₂O₃ catalyst at S/C = 4. At S/C = 1 conversion was suppressed for both gas mixtures. Single alkane reforming of C₂–C₄ showed different sensitivity for side reactions, e.g., methanation between 350 and 650 °C. These results contribute to ongoing research in the field of low-temperature hydrogen release from natural gas alkanes for fuel cell applications as well as for pre-reforming processes.

In the present day, methanol is mainly produced from methane via reforming processes, but research focuses on alternative production routes. Herein, we present a chemo-/biocatalytic oxidation cascade as a novel process to currently available methods. Starting from synthetic biogas, in the first step methane was oxidized to formaldehyde over a mesoporous VO_x/SBA-15 catalyst. In the second step, the produced formaldehyde was disproportionated enzymatically towards methanol and formic acid in equimolar ratio by formaldehyde dismutase (FDM) obtained from Pseudomonas putida. Two processing routes were demonstrated: (a) batch wise operation using free formaldehyde dismutase after accumulating formaldehyde from the first step and (b) continuous operation with immobilized enzymes. Remarkably, the chemo-/biocatalytic oxidation cascades generate methanol in much higher productivity compared to methane monooxygenase (MMO) which, however, directly converts methane. Moreover, production steps for the generation of formic acid were reduced from four to two stages.