Abstract This work presents an example of the design and manufacture capabilities that 3D printing can introduce in catalysis. A multi-purpose catalyst, with fast heat and mass transfer and low-pressure drop has been designed and manufactured by 3D printing. The novelty of the methodology is the combination of advanced techniques for accurate control on the micropore-level allied with a generic framework for the design of macropore and structural levels. The ability to design ordered macroporous should be combined with adequate and controllable implantation of surface functionalities. With this combination of advanced techniques for macro and micro-pore control, it is possible to produce catalysts that unlock traditional trade-off compromises between diffusion, pressure drop and heat transfer. To demonstrate this novel methodology, we have designed and 3D printed a cubic iso-reticular foam in AlSi10Mg. After producing the support, its entire internal area was anodized to high-surface alumina followed by Pt deposition. We have verified the reproducibility of this technique by manufacturing a catalyst for a demonstrator with 8 m length. The test reaction was oxidation of NO to NO2 with the main aim to accelerate this reaction for additional recovery of energy in the production of nitric acid.

Abstract The potential impregnation of Al(0) nanoparticles in the pores of three different metal-organic frameworks (MOFs), MIL-53-Al, HKUST-1, and UiO-67, was investigated through the suspension of the MOFs in AlH3·NMe2Et (1), followed by filtration, toluene wash, and heating to 150 °C under vacuum. Calculations based on the ratios of molecular and pore volumes provided idealized, benchmark impregnation capacities. Three successive impregnation cycles were performed to provide maximum incorporation of Al in the pores, and the materials were characterized after each impregnation cycle by ICP elemental analysis, BET surface area, and pore volume measurements. For MIL-53-Al, about half of the calculated amount of Al was incorporated into the MIL-53 pore structure, and PXRD data indicated a loss of crystallinity after the third incorporation cycle. Little Al incorporation was observed with HKUST-1, and the large decrease in surface area and pore volume, without significant change in the PXRD pattern, is attributed to pore blockage. Reaction of a large excess of 1 with UiO-67 was highly exothermic and evolved gas, likely from reaction with the μ3-OH groups in the UiO-67 structure. The resulting material was amorphous apart from metallic Al(0) crystals approximately 30 nm in size and larger than the UiO-67 pores, as determined by PXRD and 27Al MAS NMR spectroscopy. This material exhibited no apparent reaction with air or water and exposure to air gave little change in the 27Al MAS NMR spectrum. The Al(0) crystals thus appear to be protected from oxidation, presumably by the remaining UiO-67 framework.

We have evaluated the kinetics of the catalytic oxidation of NO to NO2 using a Pt/alumina catalyst, under conditions relevant to industrial nitric acid production: NO and steam contents up to 5% and 20%, respectively, with temperatures from 250 to 350 °C, and pressures up to 4.7 bar. The objective is to replace the current homogeneous oxidation process, which requires cooling of the process gas and a long residence time, with a more intensive heterogeneous oxidation process, allowing the heat of reaction (114 kJ/mol) to be recovered. This may give a 10% improvement in overall heat recovery and, additionally, lead to reduced capital expenditure (CAPEX) and footprint of new build plants. With world production of nitric acid of 60 million tonnes per annum, the transformation from the homogeneous oxidation of NO to a heterogeneous oxidation can lead to significant environmental benefits and cost reduction.

Abstract When SAPO-34 is used as an industrial MTO catalyst, structural transformations leading to permanent deactivation are inevitable. The performance loss is linked principally to a redistribution of Si in the material, leading to the formation of Si-islands/aggregates with a concomitant loss of Bronsted acidic sites and catalytic activity. In this work we have studied transformations taking place in a SAPO-34 sample after hydrothermal treatment by studying two samples with different levels of Si; 7 atomic % and 13 atomic % Si T-atoms, corresponding to about one and two Si per CHA cage respectively. The 13% Si sample contains significant amount of silicon islands in its as-synthesized form, while the 7% Si sample does not. The 7% Si sample was steamed for a week at 700 °C and a partial pressure of steam of 0.7 atm. The changes were analysed in the context of Si-island formation, and compared with the 13% Si sample. The results clearly illustrated existence of two distinct types of local aggregation of silicon: Silicon islands produced during synthesis and aggregate silicon reminiscent of silicon islands induced by hydrothermal treatment. The materials were synthesized with full 29Si isotopic enrichment and allowed us, for the first time, to characterise the multiplicity of silicon species in great detail by 29Si solid state NMR.

Abstract A metal-organic framework, UiO-66, has been evaluated as adsorbent in a post-combustion vacuum swing adsorption (VSA) process. Equilibrium isotherms of the most relevant gases (CO 2 and N 2 ) as well as breakthrough curves measured using synthetic flue gas containing 15 mol% CO 2 without and with 9 mol% water vapor are reported. Based on the breakthrough data, a six step one-column VSA cycle is designed and the effects of adsorption and CO 2 rinse times used on the CO 2 recovery and CO 2 purity are examined. With the chosen process configuration and cycle design CO 2 purities around 60% and CO 2 recoveries up to 70% are achieved. 50 cycle adsorption-desorption experiments show that the cyclic CO 2 capacity is reduced by approximately 25% in the presence of water vapor. No reduction in cyclic capacity is observed with increased cycle number; there is rather a slight increase in cyclic capacity with cycle number indicating that a cyclic steady state still not has been reached after 50 cycles.