https://doi.org/10.1016/j.catcom.2023.106610
“Direct ink writing as additive manufacturing technique was used to print two different boehmite based shapes, cylinders and monoliths, serving as catalyst carriers. These were wet impregnated targeting 0.3–0.9 wt% platinum loadings. ICP-OES, μCT and microscopy revealed dependencies from calcination temperature, geometry and platinum loading. Dehydrogenation reactions of perhydro dibenzyltoluene as liquid organic hydrogen carrier were performed examining the catalytic performance. Differences when executing full particle measurements led to the conclusion that direct ink writing as shaping technique for catalyst carriers and the respective impregnation is highly beneficial as more complex shapes can be obtained, resulting in higher activities.”
“N2 physisorption measurements were performed on a NOVAtouch analyzer (Quantachrome Instruments) at 77 K. Prior to measurement the samples were degassed under vacuum at 120 °C for 3 h. The specific surface area SBET was calculated according to the method of Brunauer, Emmett, and Teller (BET) between p/p0 = 0.05 and 0.3. According to the method of Barrett, Joyner, Halenda (BJH), the desorption branch of the isotherm was used to determine the pore size distribution.”
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By means of N2 physisorption, the specific surface area SBET was determined quantifying a decrease from 55 m2g−1 to 22 m2g−1 and hereby showing a similar trend as the total pore volume with increasing the calcination temperature. Surface area and pore volume are herein considered as material characteristics and thus primarily based on the calcination temperature rather than the shape printed. Overall pore size distributions determined via BJH method (Fig. 3) showed only mesopores and a bimodal curve for both calcination temperatures with pore radii of approximately 5 nm and 20 nm. However, sintering at higher temperatures led to a decreased amount of both, smaller and bigger pores with a much more prominent decline of the smaller pores. This finding is in accordance with common literature, showing sintering of smaller pores first. [31,64,65]
Table 2. Crushing strength σcrush, surface area SBET and total pore volume Vp of cylinders depending on their calcination temperature.
- a
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Determined via uniaxial compression tests.
- b
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Determined by N2 Physisorption.
Fig. 3. Pore size distribution of calcined cylinders determined via BJH calculations from N2 physisorption.
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