Coupled Plasma-Catalytic System with Rang 19pr Catalyst for Conversion of Tar

In-depth analysis of the effect of catalysts on plasma technologies for treatment of various wastes

Energy security and waste management are gaining global attention. The modern world is producing a large amount of liquid and solid waste as a result of the increasing population and industrialization. A circular economy encourages the conversion of waste to energy and other value-added products. Waste processing requires a sustainable route for a healthy society and clean environment. One of the emerging solutions for waste treatment is plasma technology. It converts waste into syngas, oil, and char/slag depending on the thermal/non-thermal processes. Most of all the types of carbonaceous wastes can be treated by plasma processes. The addition of a catalyst to the plasma process is a developing field as plasma processes are energy intensive. This paper covers the detailed concept of plasma and catalysis. It comprises various types of plasma (non-thermal and thermal) and catalysts (zeolites, oxides, and salts) which have been used for waste treatment. Catalyst addition improves gas yield and hydrogen selectivity at moderate temperatures. Depending on the properties of the catalyst and type of plasma, comprehensive points are listed for the selection of the right catalyst for a plasma process. This review offers an in-depth analysis of the research in the field of waste-to-energy using plasma-catalytic processes.

Toluene Decomposition in Plasma–Catalytic Systems with Nickel Catalysts on CaO-Al2O3 Carrier

The decomposition of toluene as a tar imitator in a gas composition similar to the gas after biomass pyrolysis was studied in a plasma–catalytic system. Nickel catalysts and the plasma from gliding arc discharge under atmospheric pressure were used. The effect of the catalyst bed, discharge power, initial toluene, and hydrogen concentration on C7H8 decomposition, calorific value, and unit energy consumption were studied. The gas flow rate was 1000 NL/h, while the inlet gas composition (molar ratio) was CO (0.13), CO2 (0.15), H2 (0.28–0.38), and N2 (0.34–0.44). The study was conducted using an initial toluene concentration in the range of 2000–4500 ppm and a discharge power of 1500–2000 W. In plasma–catalytic systems, the following catalysts were compared: NiO/Al2O3, NiO/(CaO-Al2O3), and Ni/(CaO-Al2O3). The decomposition of toluene increased with its initial concentration. An increase in hydrogen concentration resulted in higher activity of the Ni/(CaO-Al2O3) catalysts. The gas composition did not change by more than 10% during the process. Trace amounts of C2 hydrocarbons were observed. The conversion of C7H8 was up to 85% when NiO/(CaO-Al2O3) was used. The products of the toluene decomposition reactions were not adsorbed onto its surface. The calorific value was not changed during the process and was higher than required for turbines and engines in every system studied.

Plasma and Superconductivity for the Sustainable Development of Energy and the Environment

The main aim of this review is to present the current state of the research and applications of superconductivity and plasma technologies in the field of energy and environmental protection. An additional goal is to attract the attention of specialists, university students and readers interested in the state of energy and the natural environment and in how to protect them and ensure their sustainable development. Modern energy systems and the natural environment do not develop in a sustainable manner, thus providing future generations with access to energy that is generated from renewable sources and that does not degrade the natural environment. Most of the energy technologies used today are based on non-renewable sources. Power contained in fuel is irretrievably lost, and the quality of the energy is lowered. It is accompanied by the emissions of fossil fuel combustion products into the atmosphere, which pollutes the natural environment. Environmental problems, such as the production of gaseous and solid pollutants and their emission into the atmosphere, climate change, ozone depletion and acid rains, are discussed. For the problem of air pollution, the effects of combustion products in the form of carbon oxides, sulfur and nitrogen compounds are analyzed. The plasma and superconductivity phenomena, as well as their most important parameters, properties and classifications, are reviewed. In the case of atmospheric pressure plasma generation, basic information about technological gas composition, pressure, discharge type, electromagnetic field specification, electrode geometry, voltage supply systems, etc., are presented. For the phenomenon of superconductivity, attention is mainly paid to the interdependencies between Tc, magnetic flux density Bc and current density Jc parameters. Plasma technologies and superconductivity can offer innovative and energy-saving solutions for power engineering and environmental problems through decreasing the effects of energy production, conversion and distribution for the environment and by reductions in power losses and counteracting energy quality degradation. This paper presents an overview of the application of technologies using plasma and superconductivity phenomena in power engineering and in environmental protection processes. This review of plasma technologies, related to reductions in greenhouse gas emissions and the transformation and valorization of industrial waste for applications in energy and environmental engineering, is carried out. In particular, the most plasma-based approaches for carbon oxides, sulfur and nitrogen compounds removal are discussed. The most common plasma reactors used in fuel reforming technologies, such as dielectric barrier discharge, microwave discharge and gliding-arc discharge, are described. The advantages of solid waste treatment using plasma arc techniques are introduced. Applications of superconductors for energy generation, conversion and transmission can be divided into two main groups with respect to the conducted current (DC and AC) and into three groups with respect to the employed property (zero resistivity, ideal magnetism/flux trapping and quench transition). Among the superconductivity applications of electrical machines, devices for improving energy quality and storage and high field generation are described. An example that combines the phenomena of hot plasma and superconductivity is thermonuclear fusion. It is a hope for solving the world’s energy problems and for creating a virtually inexhaustible, sustainable and waste-free source of energy for many future generations.

Nickel catalyst in coupled plasma-catalytic system for tar removal

Tar formation is a significant issue during biomass gasification. Catalytic removal of tars with the use of nickel catalyst allows to obtain high conversion rate but coke formation on catalysts surface lead to its deactivation. Toluene decomposition as a tar imitator was studied in gliding discharge plasma-catalytic system with the use of 5%, 10% and 15% by weight Ni and NiO catalyst on Al2O3 (α-Al2O3) and Peshiney (γ-Al2O3) carrier in gas composition similar to the gas after biomass pyrolysis. The optimal concentration of nickel was identified to be 10% by weight on Al2O3. It was stable in all studied initial toluene concentrations, discharge power while C7H8 conversion rate remained high – up to 82%. During the process, nickel catalysts were deactivated by sooth formation on the surface. On catalysts surface, toluene decomposition products were identified including benzyl alcohol and 3-hexen-2-one.

Decomposition of Tars on a Nickel Honeycomb Catalyst

Biomass can be considered a renewable energy source. It undergoes a gasification process to obtain gaseous fuel, which converts it into combustible gaseous products such as hydrogen, carbon monoxide, and methane. The process also generates undesirable tars that can condense in gas lines and cause corrosion, and after processing, can be an additional source of combustible gases. This study focused on the processing of tar substances with toluene as a model substance. The effect of discharge power and carrier gas composition on toluene conversion was tested. The process was conducted in a plasma-catalytic system with a new Ni3Al system in the form of a honeycomb. The toluene conversion reached 90%, and small amounts of ethane, ethylene, acetylene, benzene, and C3 and C4 hydrocarbons were detected in the post-reaction mixture. Changes in the surface composition of the Ni3Al catalyst were observed throughout the experiments. These changes did not affect the toluene conversion.

Plasma-Catalytic Process of Hydrogen Production from Mixture of Methanol and Water

In the present work the process of hydrogen production was conducted in the plasma-catalytic reactor, the substrates were first treated with plasma and then introduced into the catalyst bed. Plasma was produced by a spark discharge. The discharge power ranged from 15 to 46 W. The catalyst was metallic nickel supported on Al2O3. The catalyst was active from a temperature of 400 °C. The substrate flow rate was 1 mol/h of water and 1 mol/h of methanol. The process generated H2, CO, CO2 and CH4. The gas which formed the greatest amount was H2. Its concentration in the gas was ~60%. The conversion of methanol and the production of hydrogen in the plasma-catalytic reactor were higher than in the plasma and catalytic reactors. The synergy effect of the interaction of two environments, i.e., plasma and the catalyst, was observed. The highest hydrogen production was 1.38 mol/h and the highest methanol conversion was 64%. The increased in the discharge power resulted in increasing methanol conversion and hydrogen production.

Integrated gasification and non-thermal plasma-catalysis system for cleaner syngas production from cellulose

An innovative integrated gasification and plasma-catalytic system has been developed to produce cleaner syngas from a model biofeedstock (α-cellulose). The influence of Co/γ-Al2O3 catalyst on the plasma reforming of tar-contaminated syngas has been investigated using a cylindrical dielectric barrier discharge reactor. The results show that plasma-catalytic processing of the syngas from biomass gasification significantly reduces the concentration of tars by 88% and enhances the total gas product yield and the syngas ratio (H2/CO) by up to 90%.