Efficient Catalytic Microreactors with Atomic‐Layer‐Deposited Platinum Nanoparticles on Oxide Support

Abstract

Microreactors attract a significant interest for chemical synthesis due to the benefits of small scales such as high surface to volume ratio, rapid thermal ramping, and well-understood laminar flows. The suitability of atomic layer deposition for application of both the nanoparticle catalyst and the support material on the surfaces of channels of microfabricated silicon microreactors is demonstrated in this research. Continuous-flow hydrogenation of propene into propane at low temperatures with TiO -supported catalytic Pt nanoparticles was used as a model reaction. Reaction yield and mass transport were monitored by high-sensitivity microcoil NMR spectroscopy as well as time-of-flight remote detection NMR imaging. The microreactors were shown to be very efficient in propene conversion into propane. The yield of 100 % was achieved at 50 °C with a reactor decorated with Pt nanoparticles of average size of roughly 1 nm and surface coverage of 3.2 % in 20 mm long reaction channels with a residence time of 1100 ms. The activity of the Pt catalyst surfaces was on the order of several to tens of mmol s m .

From Single Atoms to Nanoparticles: Autocatalysis and Metal Aggregation in Atomic Layer Deposition of Pt on TiO2 Nanopowder

“…Interestingly, the PSDs obtained at high oxygen pressures are consistent with a recent report on Pt ALD on TiO 2 (flat substrate) using oxygen plasma at 300 °C as the oxidizer . In fact, also Rontu et al report the formation of NPs of 1–2 nm after five ALD cycles. It is reasonable to assume that the oxygen plasma used by Rontu et al insured the complete combustion of the carbon ligands.…”

“…In fact, also Rontu et al report the formation of NPs of 1–2 nm after five ALD cycles. It is reasonable to assume that the oxygen plasma used by Rontu et al insured the complete combustion of the carbon ligands. This reinforces our conclusion that NPs >1 nm can emerge even after only few ALD cycles provided that the carbon ligands are removed and that atom diffusion is active.…”

“…Although ALD of thin films on flat substrates is a mature technology, ALD of NPs on high‐surface‐area supports is still poorly understood . For example, ALD of platinum NPs results in very different PSDs depending on the reaction conditions, reactor configuration, and nature of the support . Mackus et al argued that in Pt ALD the NP size depends on the oxygen exposure during the ligand‐removal step because the presence of oxygen affects the mobility of Pt species and thus the aggregation of atoms into NPs, which in turn can catalyze combustion reactions.…”

Standalone micro-reformer for on-demand hydrogen production from dimethyl ether

“…For an increasing number of ALD cycles, a broader particle distribution was indeed expected as shown before by Rontu et al [41]. Surface chemical modification is thereby pointed out as an effective route to obtain more hydroxyl-terminate surface, thus reducing the number of ALD cycles and obtaining a narrower distribution and smaller particles, usually more active in catalysis.…”

Microfabrication atomic layer deposited Pt NPs/TiN thin film on silicon as a nanostructure signal Transducer: Electrochemical characterization toward neurotransmitter sensing

“…The other sample type, designated as "TiN/ Air", was cooled down in air, allowing the surface to oxidize. Pt was deposited by ALD using MeCpPtMe 3 and O 2 -plasma under the optimized parameters reported previously [36]. MeCpPtMe 3 was heated to 55 • C to achieve enough vapor pressure.…”