High Temperature Catalytic Reactors Research Articles

Ammonia energy storage for hybrid electric aircraft

This work considers the development of a hybrid electric vertical takeoff and landing aircraft with an NH3 engine. An NH3 cracker with an external heat supply from the engine and a high-temperature catalytic reactor is needed to crack part of the NH3 in H2 and N2. The engine has two turbochargers in cascade, an intercooler, and an SCR catalyst with additional NH3 injection before the catalyst to control emissions. The H2 is used to ignite an NH3 mixture which may also be enriched with hydrogen to address particularly slow-burning points. The proposed learn burn engine which features direct injection and jet ignition of H2 may have power densities above 100 kW per liter and fuel conversion efficiencies approaching 50%. This engine can be further specialized to work on a narrow range of speeds and loads, ideally, one single point, to produce electricity on board the aircraft. The energy storage per unit mass of the complete system is expected to reduce vs. diesel but not dramatically. Importantly, it is much better than the storage of energy in a battery.

A novel process for the coproduction of biojet fuel and high-value polyunsaturated fatty acid esters from heterotrophic microalgae Schizochytrium sp. ABC101

Herein we demonstrated an economically beneficial process coproducing biojet fuel and high-value polyunsaturated fatty acids (PUFAs) from Schizochytrium sp. ABC101 microalgae. Schizochytrium is a promising biofuel source for its rapid growth, high cell density, and fast lipid accumulation via heterotrophic cultivation. The most important feature of Schizochytrium is that half of its lipids are composed of omega-3 PUFAs (i.e., docosahexaenoic acid and docosapentaenoic acid), which are currently commercialized as dietary supplements at a high price. We observed direct injection of PUFA-rich lipid into a high-temperature catalytic reactor can cause rapid catalyst deactivation via coke deposition. Therefore, the PUFAs were separated by short-path distillation after transesterification. The remaining esters of saturated fatty acids (SFAs) were catalytically deoxygenated into C13–C18n-paraffins, and then subsequently hydrocracked to produce iso-rich paraffins that are suitable as biojet fuel. As the result, 54.6 wt% PUFA-enriched esters (purity: 87.7%) and 20.4 wt% of qualified biojet fuel with respect to the initial lipids were obtained.

The deactivation of the decomposition catalyst of chemical-recovery ammonia

The results of the monitoring of decomposition furnaces carried out for 5.5 years at OAO Metallurgical Combine Magnitogorsk has been analyzed. It was found that the rate of the irreversible deactivation of nickel catalyst G1–11 produced by the BASF company during the industry decomposition process of chemical-recovery ammonia under temperature higher than 1100°C is 0.39 dB/year (∼10% per year). The high activity of the modified catalyst KDA-18A (developed by NIAP, Novomoskovsk) makes it promising to use as the catalyst in the thermocatalytic decomposition of chemical-recovery ammonia. The new construction of a high temperature catalytic reactor allows for the use of the catalyst.

Environmental Impact Assessment for Potential Continuous Processes for the Production of Carbon Nanotubes

As an emerging discipline, nanotechnology has the potential to improve environmental sustainability through its application in pollution prevention, treatment, remediation, etc. One challenging issue in the growth of nanotechnology is how to produce purified carbon nanotubes (CNT) in commercial quantities at affordable price and with low environmental impacts. A detailed assessment of such a manufacturing process from both economic and environmental aspects at the design phase will benefit both the industry and the society. In this work, an LCA type of environmental impact assessment is conducted for the conceptual design of two catalytic, chemical vapor deposition processes (CNT-PFR and CNT-FBR) used for continuous large-scale production of CNT. The core of both processes is a high-temperature catalytic reactor. Mineral acids are used in the purification steps, from which liquid and solid wastes are generated and must be treated before discharge. Based on the simulation results, the environmental impacts of each process are calculated. The results provide vital information that can be used during the design phase of these processes for better decision-making.