Technical and economic operation parameters of a high-temperature plasma plant for production and consumption waste conversion (calculation results and their analysis)

Principal technical and economic operation parameters of the high-temperature plasma waste conversion plant (production of electricity, heat, and basaltiform slag, amount of waste disposed, profitability, payback period, etc.) are presented. The combination of plasma waste conversion and electricity generation with the help of the self-produced pyrolysis gas provides a high profitability index and an acceptable payback period.     

Development of plasma techniques for solid radioactive waste processing

The analysis of development of plasma methods of processing of a waste is carried out. Technological, ecological and economic aspects of plasma processing on the basis of the Russian and foreign data are considered. The comparative analysis of efficiency plasma and traditional methods of processing of the radioactive waste is carried out and perceptivity of the further development of plasma technology of processing of a radioactive waste is shown.     

Non-thermal plasma technology for the conversion of CO2

The conversion of carbon dioxide is vital if we are to avoid the catastrophic consequences that will result from further global temperature rise as a result of burning fossil fuels. Current techniques, such as catalytic conversion and biochemical processes, are each associated with their own drawbacks such as catalyst deactivation and high energy input. Plasma processes are gaining increasing interest as they have the potential to reduce a greater amount of atmospheric environmental pollutants at any one time due to an increased throughput, whilst using a smaller reactor with improved energy efficiency and near-zero emissions. Non-thermal plasma can dissociate stable molecules, such as CO₂, at temperatures as low as room temperature. It is this key feature which makes plasma conversion such a promising technology in the conversion and utilisation of CO₂. Furthermore, possible products from plasma processes include fuels and chemicals, such as methanol and syngas, which have a high market value; hence potentially making the process feasible on an industrial scale. This paper discusses recent advances in the use of plasma processes for carbon dioxide conversion, along with the future outlook of this technology and the impact these techniques could have on the chemical and energy industries.     

射频等离子体热解废轮胎的研究

Disposal of the huge piles of used tires is increasingly becoming a problem all over the world. Incineration may utilize the energy content of waste tires, but it is associated with the generation of SO2, NOx and other hazardous emissions. Pyrolysis is an alternative disposal method with the possibility for recovery of valuable products from used tires. Recently, waste processing technology based on plasma processes has received much attention due to a number of advantages such as high treatment rate, small space volume, etc. In this paper, the pyrolysis of waste tire using a capacitively coupled radio-frequency （RF） plasma reactor was investigated. The lab-scale RF plasma reactor was operated with RF powers between 1 600 W and 2 000 W, pressures between 3 000 Pa and 8 000 Pa （ absolute pressure） and temperatures between 1 200 K and 1 800 K. In the tire powder pyrolysis experiments, two product streams are obtained： combustible gas and char. The physical properties （surface area, porosity, particle morphology） as well as chemical properties （elemental composition, heating value and surface functional groups） of char were examined to exploit the potential applications of the char. The results indicate that the RF plasma pyrolysis would be a useful technology for waste disposal.     

脉冲电晕等离子体作用下CH4/H2反应的机理

本文利用发射光谱技术,对脉冲电晕等离子体作用CH4/H2反应进行了原位诊断,根据等离子体作用下CH4、H2和CH4/H2体系中部分激发态物种的光谱检测数据和有关实验的结果,结合等离子体特性及小分子光化学反应规律,对等离子体作用CH4/H2转化制备C2烃反应的机理进行了讨论。     

废弃塑料光催化转化制备低碳数有机化合物

大量废弃塑料引发了一系列的环境和生态问题,其转化和利用一直受到广泛关注.塑料中含有丰富的碳元素,但这些碳元素往往以惰性的C–C键和C–H键形式存在,因此如何利用这些碳资源成为一大难题和挑战.以往部分研究已经提供了塑料催化转化制备碳材料、化学品和燃料的可能性,但是自然界中的废弃塑料总量庞大,需要考虑其转化过程中的能量来源.地球上有丰富的太阳能资源,光催化过程有可能利用太阳能来实现温和条件下的废弃塑料转化.在以往的研究中,光催化塑料降解和光催化塑料重整过程主要关注的目标产物分别是CO₂和H₂.相较而言,光催化塑料转化制备低碳数有机化合物的过程有望助力碳循环经济的发展.近年来报道了一些光催化塑料转化制备低碳数有机化合物的研究工作,这些研究为获取和利用塑料中的碳资源提供了新的研究思路和策略.本文概括对比了光催化塑料降解、光催化塑料重整和光催化塑料转化制备低碳数有机化合物三种过程的差异,包括其中的目标产物和相应的反应活性物种.此外,本文总结了光催化塑料转化制备低碳数化合物的反应方法.简要地说,塑料可以经过光催化选择性氧化、氧化偶联和水解脱氢等策略来得到低碳数的化学品和燃料,涉及利用光催化氧化过程断裂塑料中的C–C键,利用水解过程断裂塑料的C–N和C–O键,以及利用光催化脱氢过程断裂中间产物的O–H键和N–H键等关键步骤.在光催化塑料转化到低碳数有机产物的文献报道中,主要涉及液固相反应体系和反应器,需要考虑反应溶剂的选择.水是理想的溶剂,但对塑料的溶解能力有限.当使用其他有机溶剂时,需要利用同位素标记实验验证产物中的碳物种来源.此外,实际废弃塑料上残留的其他杂质会影响光催化剂的吸光过程,降低光催化反应效率,因此亟需设计和开发合理的光反应器来提高对光能的利用率,实现塑料的高效转化.虽然塑料制备低碳数化学品和燃料的光催化转化策略已有研究报道,但未来仍需探索更加高效的转化路线.此外,塑料主要呈现高分子聚合物的结构,未来的研究可以借鉴对生物质等天然聚合物分子的转化策略.     

Catalysts developed from waste plastics: a versatile system for biomass conversion

The end-of-life treatment for post-consumer plastic waste constitutes one of modern society’s greatest problems, whereby highly unsustainable landfilling and incineration are the two main disposal routes. At present, the chemical upcycling of plastic waste is largely limited to its pyrolytic conversion into hydrocarbon fuels or nanomaterials. Herein, we demonstrate the upcycling of high-volume plastic waste by turning them into catalysts for biomass valorization. Many existing studies synthesize organocatalysts from a bottom-up approach using specialized monomers. Yet, transforming widely available waste polymers into functionalized materials for catalysis remains relatively unexplored. In this study, homogeneous and cross-linked heterogeneous catalysts derived from waste polystyrene food containers are shown to convert readily available saccharide precursors from biomass into 5-hydroxymethylfurfural (5-HMF), a key biorefinery platform chemical, under short reaction times and mild conditions. In addition, the heterogeneous catalyst can be reused multiple times with little loss of yield between repeated runs. Other than 5-HMF, doping the reaction with water or halide salts also allowed the formation of valuable products such as formic acid and diformylfuran. Our work expands on existing upcycling options for post-consumer plastic waste by giving them a new lease of life as value-added catalysts.     

Methane conversion in low-temperature plasma

The conversion of methane in electric discharges of different types and under electron beam irradiation are considered. The influence of nonequilibrium conditions of conversion in low-temperature plasma on the energy consumption, product composition, and selectivity is analyzed. The results of works on plasma pyrolysis, partial plasma oxidation, and steam and carbon dioxide reforming of methane in a low-temperature plasma are discussed. It is shown that the use of chain processes makes it possible to substantially reduce the power consumption for methane conversion by an electrophysical device.     

Enzymatic conversion of waste cooking oils into alternative fuel—Biodiesel

Production of biodiesel from pure oils through chemical conversion may not be applicable to waste oils/fats. Therefore, enzymatic conversion using immobilized lipase based on Rhizopus orzyae is considered in this article. This article studies this technological process, focusing on optimization of several process parameters, including the molar ratio of methanol to waste oils, biocatalyst load, and adding method, reaction temperature, and water content. The results indicate that methanol/oils ratio of 4, immobilized lipase/oils of 30 wt% and 40°C are suitable for waste oils under 1 atm. The irreversible inactivation of the lipase is presumed, and a stepwise addition of methanol to reduce inactivation of immobilized lipases is proposed. Under the optimum conditions the yield of methyl esters is around 88–90%.     

Thermochemical conversion of coconut waste: material characterization and identification of pyrolysis products

Journal of Thermal Analysis and Calorimetry - In this work, coconut waste was evaluated for its potential for biofuel production via pyrolysis by considering physicochemical properties, kinetics of...     

环境固体废物的监测技术及其应用

介绍了固体废物的特点和分类、我国固体废物监测技术的发展历程及现有固体废物的监测及管理标准体系,在此基础上列举了具有代表性的测定固体废物中污染物的前处理及监测技术应用实例。     

Russian experience in solid radioactive waste processing: Achievements and prospects

Plasma technology not only solves the problem of the elimination of the newly formed NPP operational waste, but also provides deep thermal processing of radioactive waste accumulated before or compacted in drums to make room for storage of solid radioactive waste.     

废旧塑料回收利用技术的现状及发展趋势

本文详细综述了从３０年代到现在国内外废旧塑料再生利用技术发展的过程及近几年废塑料回收最新技术,对未来废旧塑料回收利用技术的发展趋势进行了预测     

Problem of utilization of solid production and consumption wastes. Plasma treatment of solid wastes

Plasma technology allows organizing a highly effective and pollution-free waste conversion and offers significant advantages over traditional technologies when waste is either incinerated or disposed in a landfill.     

Recycling of polymers used in aerospace industry. Treatment by plasma process

AEROSPATIALE has, for more than 20 years, developed and perfected a device intended to simulate the atmospheric re-entry conditions: the plasma torch. This technology, developed for the needs of space industry, is also applicable in other industrial fields like metallurgy or waste disposal. For most residues, as, for instance, for polymer residues (in particular for composite materials), incineration is the best solution to be considered. Although the organic molecule may be a real danger for man and his environment, it is possible to split it into elementary molecules easy to eliminate without risks by the simultaneous application of heat and a specific chemical environment. The use of additives in the polymers makes it necessary in most cases to use temperatures as high as possible; these high temperatures have the additional advantage of preventing harmful recombinations in the reaction chamber. Only plasma processes give the possibility to ensure high temperatures in large capacity chambers in a controlled atmosphere.     

Methane conversion by an air microwave plasma

Activation of methane is carried out by means of an air microwave plasma (2.45 GHz). The experiments cover the absorbed microwave power range 350–650 W (20–50 W cm³ with 17–62%, of methane in the gas mixture, with pressures of 10–66 mbar and flow rates of 140700 ml min¹. Methane, dioxygen, and dinitrogen consumptions as well as C₂ hydrocarbons, carbon monoxide, and dihydrogen yields are analyzed hr gas chromatography. The distance of methane addition from the end of the discharge plays an important role in the composition and the concentration of the products obtained. This distance mainly determines the energy concentrated in the active species of the plasma when they react with methane. A kinetic mechanism jar the activation and decay of inethane and for the formation of C₂ hydrocarbons and carbon monoxide is discussed based on the experimental results and kinetic data in the literature.     

Nickel-catalyzed selective conversion of two different aldehydes to cross-coupled esters

In the presence of a Ni(0)/NHC catalyst, an equimolar mixture of aliphatic and aryl aldehydes can be employed to selectively yield a single cross-coupled ester. This reaction can be applied to a variety of aliphatic (1°, 2°, cyc-2°, and 3°) and aryl aldehyde combinations. The reaction represents 100% atom efficiency and generates no waste. Mechanistic studies have revealed that the striking feature of the reaction is the simultaneous coordination of two aldehydes to Ni(0).     

Biomass conversion to mixed alcohol fuels using the MixAlco process

The MixAlco process is a patented technology that converts any biodegradable material (e.g., sorted municipal solid waste, sewage sludge, industrial biosludge, manure, agricultural residues, energy crops) into mixed alcohol fuels containing predominantly 2-propanol, but also higher alcohols up to 7-tridecanol. The feed stock is treated with lime to increase its digestibility. then, it is fed to a fermentor in which a mixed culture of acid-forming microorganisms produces carboxylic acids. Calcium carbonate is added to the fermentor to neutralize the acids to their corresponding carboxylate salt. The dilute (−3%) carboxylate salts are concentrated to 19% using an amine solvent that selectively extracts water. Drying is completed using multi-effect evaporators. Finally, the dry salts are thermally converted to ketones which subsequently are hydrogenated to alcohols. All the steps in the MixAlco process have been proven at the laboratory scale. A techno-economic model of the process indicates that with the tipping fees available in New York ($126/dry tonne), mixed alcohol fuels may be sold for $0.04/L ($0.16/gal) with a 60% return on investment (ROI). With the average tipping fee in the United States rates ($63/dry tonne), mixed alcohol fuels may be sold for $0.18/L ($0.69/gal) with a 15% ROI. In the case of sugarcane bagasse, which may be obtained for about $26/dry ton, mixed alcohol fuels may be sold for $0.29/L ($1.09/gal) with a 15% ROI.     

Cellulosic materials recovered from steam classified municipal solid wastes as feedstocks for conversion to fuels and chemicals

Applied Biochemistry and Biotechnology - A process has been developed for the treatment of municipal solid waste to separate and recover the cellulosic biomass from the nonbiomass components. The...     

Watergas from plastic waste and its possible uses

Coal gasification technology should also be applicable to plastic waste. The resulting product is watergas or in general terms syngas which is used as a feedstock for several large chemical products. Based on theoretical considerations the study evaluates the costs related to syngas production from plastic waste and subsequent conversion to chemical raw products. Net waste disposal costs of 275 – 690 DM/ton are calculated depending upon the end product(s).