Estimation of pyrolysis product of LDPE degradation using different process parameters in a stirred reactor

Pyrolysis of low density polyethylene (LDPE) by equilibrium fluid catalytic cracking (FCC) was studied in a stirred reactor under different process parameters. In this work, the effect of process parameters such as degradation temperature (420-510°C), catalyst/polymer ratio (0-60%), carrier gas type (H2, N2, ethylene, propylene, Ar and He), residence time and agitator speed (0-300 rpm) on the condensate yield (liquid, gas and coke) and product composition were considered. Reaction products were determined by GC analysis and shown to contain naphthenes (cycloalkanes), paraffins (alkanes), olefins (alkenes) and aromatics. Higher temperature and more catalyst amount enhanced LDPE cracking. The maximum “fuel like” condensed product yield was attained at 450°C and 10% catalyst, respectively and gaseous products increased with increases in temperature. Hydrogen as a reactive carrier gas increased the condensed and paraffinic product yield. Appropriate heat transfer (by stirring) increased the catalyst efficiency in a stirred reactor

Effect of temperature, heating rate and zeolite-based catalysts on the pyrolysis of high impact polystyrene (HIPS) waste to produce fuel-like products

Pyrolysis of high impact polystyrene (HIPS) waste has been investigated under different process parameters, such as temperature, heating rate and types of zeolitic catalysts to produce valuable liquid products. Liquid, gas and coke as products of pyrolysis and aromatic, naphthene, olefin and paraffin as liquid components were obtained and their molecular weight distributions were studied with changing the process parameters in a stirred reactor. Aromatic-rich hydrocarbons within the gasoline range were the main pyrolysis products. Type of zeolitic catalysts, temperature and heating rate had significant effects on the products quality and quantity. Non-isothermal mass losses of high impact polystyrene were measured using a thermo-gravimetric analyzer (TGA) at heating rates of 5, 15, 30, 45 and 90°C min-1 until the furnace wall temperature reached 600°C. The DTG (differential thermal gravimetric) curves showed that heating rate had no obvious effect on the degradation trends in the studied range, and by increasing heating rate, the activation energies were decreased obviously from 222.5 to183.6 kJ mol-1

CeO2 and La2O3 promoters in the steam reforming of polyolefinic waste plastic pyrolysis volatiles on Ni-based catalysts

[EN] Based on the promising results of La2O3 and CeO2 promoted Ni/Al2O3 catalysts in the reforming of biomass pyrolysis volatiles, the performance of these catalysts and the non-promoted one was 2 evaluated in the pyrolysis and in-line steam reforming of polypropylene (PP). The experiments were carried out in a continuous bench scale pyrolysis-reforming plant using two space times of 4.1 and 16.7 gcat min gplastic−1 and a steam/PP ratio of 4. The prepared catalysts and the deposited coke were characterized by N2 adsorption-desorption, X-ray fluorescence (XRF), X-ray diffraction (XRD), temperature programmed oxidation (TPO) and transmission electron microscopy (TEM). The Ni/Al2O3 catalyst showed suitable performance regarding pyrolysis product conversion and hydrogen production, and led to moderate coke deposition. It is to note that La2O3 incorporation remarkably improved catalyst performance compared to the other two catalysts in terms of conversion (> 99 %), hydrogen production (34.9 %) and coke deposition (2.24 wt%).This work was carried out with the financial support from Spain’s ministries of Economy and Competitiveness (CTQ2016-75535-R (AEI/FEDER, UE), Science, Innovation and Universities (RTI2018-101678-B-I00 (MCIU/AEI/FEDER, UE)) and, Science and Innovation PID2019-107357RB-I00 (MCI/AEI/FEDER, UE)), the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 823745, and the Basque Government (IT1218-19 and KK-2020/00107)

The production of high efficiency Ziegler–Natta catalyst with dual active sites nature using cyclohexyl chloride as promoter with super activity and produced superior polyethylene with controllable molecular weight distribution

In the previous studies, the several halocarbons (HC) were tested as promoters for a Ti-based Ziegler–Natta (ZN) catalyst at different polymerization conditions. The Results showed that chloro cyclohexane has the best operation in catalyst activity, polymer particle size growth, hydrogen responsibility and wax reduction too. For the first time in this study, the effect of Al/Ti ratio on the optimum HC/Ti ratio has been considered and the results showed that the optimum HC/Ti ratio depends on the Al/Ti ratio directly. In the optimum HC/Ti ratio, the catalyst activity and hydrogen responsibility ratio of the catalyst increase up to 125 and 55% respectively. The acceptable growth of polymer powder up to 46%, lower flow rate ratio (FRR) up to 19% and decrease of wax amount up to 12%, completed the promotion results. Furthermore, in the next part of this study and as key note, a little dose of halocarbon was used in the catalyst preparation to produce the special catalysts with dual active sites. In the catalyst preparation, the concentration of each active sites depends on the halocarbon amount and it can control the molecular weight distribution of the produced polyethylene; because each active sites have different response to hydrogen. The halocarbon based catalysts showed the remarkable effect on the catalyst activity, the molecular weight and especially molecular weight distribution (MWD). The flow rate ratio and MWD could be increased up to 77 and 88% respectively as the main result of halocarbon addition during the catalyst preparation

A comprehensive experimental investigation of plastic waste pyrolysis oil quality and its dependence on the plastic waste composition

Pyrolysis of plastic packaging waste yields a liquid product that can be processed in steam crackers producing light olefins and hence closing the loop towards new virgin plastics. However, there is a lack of knowledge on how the plastic waste composition affects the pyrolysis oil quality regarding hydrocarbon composition and contaminant concentrations. The associated uncertainty is a key reason why thermochemical recycling of contaminated plastic waste is not yet industrially established. In this study, post-consumer plastic packaging waste fractions, namely mixed polyolefins (MPO), polyethylene (PE), and polypropylene (PP) were processed in a continuous pilot-scale pyrolysis unit and the pyrolysis oils subsequently characterized using advanced analytical techniques such as two-dimensional gas chromatography. Substantial amounts of branched olefins (~63 wt%) and diolefins (~20 wt%) were detected in the pyrolysis oil of PP-rich waste, while PE-rich waste produced high amounts of linear paraffins (~34 wt%) and olefins (~26 wt%). Furthermore, significant amounts of nitrogen, oxygen, chlorine, iron, sodium and silicon were detected in the pyrolysis oils exceeding feedstock specifications for industrial steam crackers by orders of magnitude. The results show that next to improved waste sorting and separation processes, pre- and post-treatment techniques are required to produce pyrolysis products suitable for chemical processing

Highly selective conversion of mixed polyolefins to valuable base chemicals using phosphorus-modified and steam-treated mesoporous HZSM-5 zeolite with minimal carbon footprint

The iron and steel industry is a carbon-intensive industry and one of the largest industrial sources of CO2 emissions. In this work, we show how the steel mill gases can be conditioned using three metal oxides to produce a CO/CO2 stream that can be used for the production of chemicals, thereby preventing the emission of carbon to the atmosphere as CO2. Abundant oxides of iron and manganese, characterised by their readiness to capture and release gaseous O2, and calcium oxide, characterised by its capacity to capture and release gaseous CO2 can be deployed in this process. Process analysis indicates that by fully utilising the chemical energy of the carbon-rich blast furnace gas (BFG) of the steel mill, 37% of the associated CO2 emissions can be eliminated. A techno-economic evaluation shows that further reduction of CO2 emissions is viable. Preliminary estimations indicate that the cost for processing BFG through the proposed process is 46 EUR2020 per tonneBFG. The sources of revenue are the product CO/CO2 stream (0.2 tonneproduct per tonneBFG) and electricity constituting 85% and 14% of the total revenue with the remaining 1% obtained by the sale of spent metal oxides used in the process. The technical feasibility of the process was experimentally proven in a fixed bed reactor to produce a CO/CO2 stream and an H2O-rich stream while the metal oxides were periodically regenerated in alternating redox conditions. Thirty executed cycles indicated stable performance of the process. The proposed process concept can be applied to any gas stream containing CO2 and fuel.Catalytic fast pyrolysis of polyolefinic waste streams was investigated to recover valuable base chemicals at high selectivity. HZSM-5 zeolite with different properties, affected by Si/Al, mesoporosity, phosphorus stabilization, and steaming, were tested and thoroughly characterized. Different feeds, catalyst/feed ratios and reaction temperatures were evaluated in a micropyrolysis reactor coupled to two-dimensional gas chromatography. While unmodified HZSM-5 rapidly deactivated, phosphorus-modified and steamtreated HZSM-5 showed almost no deactivation due to its lower coking propensity during 130 runs with stable conversion towards C5+ aliphatics and high C-2-C-4 olefins selectivity (-75%) using post-consumer mixed polyolefins. The performance of this direct olefins production route with unprecedented high olefin selectivity was further evaluated in a plantwide context. It was found that it requires-37% lower energy input than the plastics pyrolysis followed by pyrolytic oil steam cracking, while it results to at least a one order of magnitude lower environmental burden as compared to waste incineration