Chemical Recycling Methods Research Articles

CO-PYROLYSIS OF POLYPROPYLENE WITH PETROLEUM OF BACIA DE CAMPOS

In this study, the process of co-pyrolysis of polypropylene (PP) residues with gas-oil was evaluated, varying the temperature and the amount of polypropylene fed to the reactor. The polypropylene samples and gas-oil were submitted to the thermal co-pyrolysis in an inert atmosphere, varying the temperature and the amount of PP. The influence of the gas-oil was evaluated carrying the co-pyrolysis in the absence of PP. The pyrolysed liquids produced by this thermal treatment were characterized by modified gaseous chromatography in order to evaluate the yield in the range of distillation of diesel. As a result, the increase of PP amount lead to a reduction in the yield of the pyrolytic liquid and to an increase of the amount of solid generated. The effect of temperature increase showed an inverse result. The results show that plastic residue co-pyrolysys is a potential method for chemical recycling of plastic products.

Chemical recycling of municipal waste slag by using phase separation

A chemical recycling method by using phase separation was applied to municipal waste slags. Glasses were prepared from incineration ash and ash-melted slag, where B(2)O(3) was added to promote phase separation. The glasses were heat-treated at temperatures higher than their glass transition temperatures, and they were soaked in hydrochloric acid, leaching CaO, Fe(2)O(3), K(2)O, and S. Transparent and colorless solids containing ca. 80 mass% of SiO(2) were successfully obtained as residues. It was suggested that phase separation took place not in the heat-treatment but in the vitrification process, and further characterizations are however required to investigate the phenomena at microscopic levels in the recycling processes.

A Comparison of Gasification with Pyrolysis for the Recycling of Plastic Containing Wastes

In the present investigation, pyrolysis and gasification, two widely used thermochemical processes, are compared as potential chemical recycling methods for MWP and plastic rich MSW in terms of products of high value and their end uses. High temperature pyrolysis results in a wide spectrum of products which also contain monomers of C2-C4 range such as ethylene and 1,3-butadiene. Recovery of monomers from their isomers and other products is difficult and energy-intensive. Gasification breaks solid wastes into simple molecules (mainly CO & H2) which subsequently can be converted to value added liquid chemicals (namely alcohols) by a catalytic synthesis processes. Synthetic alcohol then can be converted to the desired petrochemical precursors. After reviewing different aspects of both pyrolysis and gasification, recycling through gasification is chosen as the preferred route for project SPORT as syngas product can be converted into several key petrochemical products in high yield.

Polyethylene Terephthalate Chemical Recycling in the Melted State

In this work the results of research on polyethylene terephthalate depolymerization by the chemical recycling method in the fused state with use of alkalis are submitted. The potential of terephthalic acid and ethylene glycol reception from polymer with addition of alkalis in the melt is shown. It is established that calcium hydroxide is the optimal reagent for performing the depolymerization reaction. This method of chemical recycling does not have the demands of high temperature and pressure, it is realized in a short time and it results in products with the high cleanliness.

Decomposition of GFRP in Nitric Acid and Hydrogen Peroxide Solution for Chemical Recycling

Decomposition of Glass Fiber Reinforced epoxy resin cured with amine in nitric acid and hydrogen peroxide solution has been investigated. After specimens were immersed in above solutions for a specific time, glass fiber could be separated from matrix resulting from the decomposition of matrix resin. The chemical structures and molecular weight distributions of the decomposed products were analyzed by FT-IR and size exclusion chromatography (SEC). When nitric acid was used, the resin was mainly decomposed into 2,4,6-trinitrophenol (picric acid) and quasi-monomer. In the case of hydrogen peroxide, the backbone of resin was broken into monomer and dimer, or peracetic acid, depending on immersion time. On the other hand, glass fiber exhibited low corrosion resistance to nitric acid, while it was hardly degraded in hydrogen peroxide. Based on analyzing the decomposed products and observing the degradation of glass fiber, the chemical recycling method on GFRP was proposed.

廃プラスチック混合物の連続油化プロセスの開発

A Increasing amount of waste plastics which causes serious pollution problem is a cheap and abundant source of chemicals and energy.The chemical recycling method, which converts waste plastics to useful hydrocarbons and monomers of the plastics, is recognized as a useful approach. The waste generated from factories is almost a specific resin, and the chemical recycle technology is being established for each plastics.However, the waste generated from household is mixture of the waste plastics.The technology developed for each plastics from factories is scarcely applicable for the waste from household.Here, a possible process, which enables to convert the mixture of waste plastics to fuels, is proposed.The key technologies of this process are; one is the usage of steam as a carrier gas, which accelerates the hydrolysis of oxygen-containing resin, the second the iron and Ni supporting REY zeolite catalysts, which show high activity in steam atmosphere, the third is a new type reactor with moved particles as a heat-medium for the pyrolysis.The utility of this process was examined by applying it to recover fuels from the mixture of poly-ethylene and poly (ethyleneterephthalate).

Chemical Recycling of Poly(ethylene terephthalate)

This paper reviews the state of the art in the field of chemical recycling of poly(ethylene terephthalate) (PET). Advantages of the chemical recycling of PET, the theoretical basis of the ester bond cleavage, and a wide spectrum of degrading agents and final products are presented. Chemical processes applied in polymer recycling are divided into six groups: methanolysis, glycolysis, hydrolysis, ammonolysis, aminolysis, and other methods. Numerous possibilities for the utilization of waste PET as a very useful raw chemical material are described on the basis of literature. A comparison of chemical recycling methods is carried out. The following aspects were taken into consideration: (i) flexibility in utilizing a variety of waste types, (ii) conditions necessary for degradation including safety requirements, (iii) economic aspects, and (iv) product versatility. A total of 108 references including 46 patents are cited in this paper.

リサイクリング 廃プラスチックの資源リサイクルについて

The material recycling rate of the plastic wastes in 1995 was 11%, which means 950, 000 tons of plastic were recycled as the materials. Taking a look at them by the production sources, the plastic wastes such as the waste pieces from molding processes, off-specification products, etc. amount to about 780, 000 tons with its material recycling rate of around 98%. On the other hand, the plastic wastes from the distribution and marketing fields amount to 3.63 million tons with the recycling rate of about 5.8 %, while the household plastic wastes amount to 4.43 million tons with the recycling rate of insignificant 0.2%.The material recycling of the plastic wastes from the household are just limited to such products as PSP trays and PET bottles witch are composed of single material and of collectable nature. When it comes to the promotion of recycling of the household plastic wastes, it is dfficult to collect only single material-products, thus, the chemical and thermal recycling methods are considered important.The energy recovery by high efficient power generation and an intermediate system of collection such as the RDF method, the reduction to oil shall become important technologies. If we can reuse them successfully combining with the existing industries such as blast furnaces, cement kilns, etc., we shall be able to expect profitable recycling businesses at the reasonable cost and future development.

4490209 Plasma etching using addition

This review summarized various chemical recycling methods for PVC, such as pyrolysis, catalytic dechlorination and hydrothermal treatment, with a view to solving the problem of energy crisis and the impact of environmental degradation of PVC. Emphasis was paid on the recent progress on the pyrolysis of PVC, including co-pyrolysis of PVC with biomass/coal and other plastics, catalytic dechlorination of raw PVC or Cl-containing oil and hydrothermal treatment using subcritical and supercritical water. Understanding the advantage and disadvantage of these treatment methods can be beneficial for treating PVC properly. The dehydrochlorination of PVC mainly happed at low temperature of 250–320 °C. The process of PVC dehydrochlorination can catalyze and accelerate the biomass pyrolysis. The intermediates from dehydrochlorination stage of PVC can increase char yield of co-pyrolysis of PVC with PP/PE/PS. For the catalytic degradation and dechlorination of PVC, metal oxides catalysts mainly acted as adsorbents for the evolved HCl or as inhibitors of HCl formation depending on their basicity, while zeolites and noble metal catalysts can produce lighter oil, depending the total number of acid sites and the number of accessible acidic sites. For hydrothermal treatment, PVC decomposed through three stages. In the first region (T < 250 °C), PVC went through dehydrochlorination to form polyene; in the second region (250 °C < T < 350 °C), polyene decomposed to low-molecular weight compounds; in the third region (350 °C < T), polyene further decomposed into a large amount of low-molecular weight compounds.

4490736 Semiconductor device and method of making

This review summarized various chemical recycling methods for PVC, such as pyrolysis, catalytic dechlorination and hydrothermal treatment, with a view to solving the problem of energy crisis and the impact of environmental degradation of PVC. Emphasis was paid on the recent progress on the pyrolysis of PVC, including co-pyrolysis of PVC with biomass/coal and other plastics, catalytic dechlorination of raw PVC or Cl-containing oil and hydrothermal treatment using subcritical and supercritical water. Understanding the advantage and disadvantage of these treatment methods can be beneficial for treating PVC properly. The dehydrochlorination of PVC mainly happed at low temperature of 250–320 °C. The process of PVC dehydrochlorination can catalyze and accelerate the biomass pyrolysis. The intermediates from dehydrochlorination stage of PVC can increase char yield of co-pyrolysis of PVC with PP/PE/PS. For the catalytic degradation and dechlorination of PVC, metal oxides catalysts mainly acted as adsorbents for the evolved HCl or as inhibitors of HCl formation depending on their basicity, while zeolites and noble metal catalysts can produce lighter oil, depending the total number of acid sites and the number of accessible acidic sites. For hydrothermal treatment, PVC decomposed through three stages. In the first region (T < 250 °C), PVC went through dehydrochlorination to form polyene; in the second region (250 °C < T < 350 °C), polyene decomposed to low-molecular weight compounds; in the third region (350 °C < T), polyene further decomposed into a large amount of low-molecular weight compounds.