Development of a Multichannel Membrane Reactor with a Solid Oxide Cell Design.

In this study, we aim to adapt a solid oxide cell (SOC) to a membrane reactor for general chemical reactions to leverage the readily available multichannel design of the SOC. As a proof-of-concept, the developed reactor is tested for syngas production by the partial oxidation of methane using oxygen ion transport membranes (ITMs) to achieve oxygen separation and permeation. A La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) membrane and Ni/MgAl2O4 catalyst are used for oxygen permeation and the partial oxidation of methane, respectively. ANSYS Fluent is used to assess the reactor performance with the help of computational fluid dynamics (CFD) simulations. The membrane permeation process is chemical kinetics achieved by user-defined functions (UDFs). The simulation results show that the oxygen permeation rate depends on the temperature, air, and fuel flow rates, as well as the occurrence of reactions, which is consistent with the results reported in the literature. During isothermal operation, the product composition and the species distribution in the reactor change with the methane flow rate. When the molar ratio of fed methane to permeated oxygen is 2.0, the methane conversion and CO selectivity reach a high level, namely 95.8% and 97.2%, respectively, which agrees well with the experimental data reported in the literature. Compared to the isothermal operation, the methane conversion of the adiabatic operation is close to 100%. Still, the CO selectivity only reaches 61.6% due to the hot spot formation of 1491 K in the reactor. To reduce the temperature rise in the adiabatic operation, reducing the methane flow rate is an approach, but the price is that the productivity of syngas is sacrificed as well. In conclusion, the adaption of the SOC to a membrane reactor is achieved, and other reaction applications can be explored in the same way.

How to reduce the greenhouse gas emissions and air pollution caused by light and heavy duty vehicles with battery-electric, fuel cell-electric and catenary trucks.

The reduction of greenhouse gas emissions is one of the greatest global challenges through 2050. Besides greenhouse gas emissions, air pollution, such as nitrogen oxide and particulate matter emissions, has gained increasing attention in agglomerated areas with transport vehicles being one of the main sources thereof. Alternative fuels that fulfill the greenhouse gas reduction goals also offer the possibility of solving the challenge of rising urban pollution. This work focuses on the electric drive option for heavy and light duty vehicle freight transport. In this study, fuel cell-electric vehicles, battery-electric vehicles and overhead catenary line trucks were investigated, taking a closer look at their potential to reduce greenhouse gas emissions and air pollution and also considering the investment and operating costs of the required infrastructure. This work was conducted using a bottom-up transport model for the federal state of North Rhine-Westphalia in Germany. Two scenarios for reducing these emissions were analyzed at a spatial level. In the first of these, selected federal highways with the highest traffic volume were equipped with overhead catenary lines for the operation of diesel-hybrid overhead trucks on them. For the second spatial scenario, the representative urban area of the city of Cologne was investigated in terms of air pollution, shifting articulated trucks to diesel-hybrid overhead trucks and rigid trucks, trailer trucks and light duty vehicles to battery-electric or fuel cell-electric drives. For the economic analysis, the building up of a hydrogen infrastructure in the cases of articulated trucks and all heavy duty vehicles were also taken into account. The results showed that diesel-hybrid overhead trucks are only a cost-efficient solution for highways with high traffic volume, whereas battery overhead trucks have a high uncertainty in terms of costs and technical feasibility. In general, the broad range of costs for battery overhead trucks makes them competitive with fuel cell-electric trucks. Articulated trucks have the highest potential to be operated as overhead trucks. However, the results indicated that air pollution is only partially reduced by switching conventional articulated trucks to electric drive models. The overall results show that a comprehensive approach such as fuel cell-electric drives for all trucks would most likely be more beneficial.

The impact of diesel vehicles on NOx and PM10 emissions from road transport in urban morphological zones: A case study in North Rhine-Westphalia, Germany.

Harmful emissions like nitrogen oxide and particulate matter are one of the big challenges facing modern society. These emissions are especially apparent in agglomerations. Possible solutions to overcome this challenge within the framework of the transformation of the transport sector are the change of the transport vehicles of freight and passenger transport or changing the fuel of the vehicles. Determining the viability of both approaches requires analyses to determine which vehicles are the main polluters in urban areas. This study outlines a bottom-up approach for the calculation of road transport emissions on street level in the representative model region of North Rhine-Westphalia in Germany, considering eight different vehicle classes as well as diesel and gasoline as fuel. Part of the approach is the development of a street-section traffic volume map considering all streets in the model region using a developed multivariate linear regression model for Germany and existing traffic counts. Using the approach developed here, the urban areas of Herne, Oberhausen and Bochum were identified as hotspots with the highest specific nitrogen oxide emissions, while the urban areas of Herne, Oberhausen and Gelsenkirchen were identified as hotspots with the highest specific particulate matter emissions. A detailed investigation of Oberhausen as a representative emission hotspot showed that 91% of road transport nitrogen oxide emissions are produced by vehicles that use diesel fuel and 9% from vehicles with gasoline fuel, while gasoline vehicles account for 43% of the total distance driven and diesel vehicles for 57%. With respect to particulate matter emissions in the urban area of Oberhausen, 29% are produced by gasoline vehicles and 71% by diesel vehicles. However, only 22% of particulate matter emissions are exhaust emissions, while 78% are produced due to the abrasion of tires, brakes and the road.