Norbert Miskolczi

Processing Real-World Waste Plastics by Pyrolysis-Reforming for Hydrogen and High-Value Carbon Nanotubes

Producing both hydrogen and high-value carbon nanotubes (CNTs) derived from waste plastics is reported here using a pyrolysis-reforming technology comprising a two-stage reaction system, in the presence of steam and a Ni-Mn-Al catalyst. The waste plastics consisted of plastics from a motor oil container (MOC), commercial waste high density polyethylene (HDPE) and regranulated HDPE waste containing polyvinyl chloride (PVC). The results show that hydrogen can be produced from the pyrolysis-reforming process, but also carbon nanotubes are formed on the catalyst. However, the content of 0.3 wt.% polyvinyl chloride in the waste HDPE (HDPE/PVC) has been shown to poison the catalyst and significantly reduce the quantity and purity of CNTs. The presence of sulfur has shown less influence on the production of CNTs in terms of quantity and CNT morphologies. Around 94.4 mmol H2 g(-1) plastic was obtained for the pyrolysis-reforming of HDPE waste in the presence of the Ni-Mn-Al catalyst and steam at a reforming temperature of 800 °C. The addition of steam in the process results in an increase of hydrogen production and reduction of carbon yield; in addition, the defects of CNTs, for example, edge dislocations were found to be increased with the introduction of steam (from Raman analysis).

Comparison of real waste (MSW and MPW) pyrolysis in batch reactor over different catalysts. Part II: Contaminants, char and pyrolysis oil properties

Pyrolysis of real wastes (MPW and MSW) has been investigated at 500°C, 550°C and 600°C using Y-zeolite, β-zeolite, equilibrium FCC, MoO3, Ni-Mo-catalyst, HZSM-5 and Al(OH)3 as catalysts. The viscosity of pyrolysis oils could be decreased by the using of catalysts, especially by β-zeolite and MoO3. Both carbon frame and double bound isomerization was found in case of thermo-catalytic pyrolysis. Char morphology and texture analysis showed more coke deposits on the catalyst surface using MSW raw material. Pyrolysis oils had K, S, P Cl, Ca, Zn, Fe, Cr, Br and Sb as contaminants; and the concentrations of K, S, P, Cl and Br could be decreased by the using of catalysts.

Two stages catalytic pyrolysis of refuse derived fuel: production of biofuel via syncrude.

Thermo-catalytic pyrolysis of refuse derived fuels with different catalysts had been conducted in a two stages process due to its important potential value as fuel. The first stage was a pure thermal pyrolysis in a horizontal tubular reactor with feed rate of 0.5kg hourly. The second stage was a semi-batch process in the presence of catalysts. Results showed that the tested catalysts significantly have affected the quantity of products. E.g. gas yield could be increased with 350% related to the catalyst free case using ZSM-5, while that of pyrolytic oil was 115% over Y-zeolite. Gases consisted of mainly CO and CO(2) obtained from the tubular reactor, while dominantly hydrocarbons from the second stage. Ni-Mo-catalyst and Co-Mo-catalyst had shown activity in pyrolytic oil upgrading via in-situ hydrogenation-dehydrogenation reactions. Sulphur, nitrogen and chlorine level in pyrolytic oils could be significantly declined by using of catalysts.

Kinetic model of the chemical recycling of waste polyethylene into fuels

Tertiary recycling methods offer potential possibilities for the utilization of waste plastics. Thermal and catalytic degradation of low-density polyethylene wastes were studied in a batch reactor under mild cracking conditions to derive liquid cracking products of olefins and paraffins. Zeolite catalysts with different activities were studied: a commercial equilibrium FCC catalyst, an H form ZSM-5 catalyst, and a natural clinoptilolite containing rhyolite tuff. The catalytic processes could convert waste polymers into valuable hydrocarbons. The properties of products could be modified by the use of catalysts. The olefin content and the position of the olefinic double bonds were investigated with IR spectrometry. In the presence of catalysts the olefin content increased, and the terminal bonds migrated into internal positions. Furthermore the liquid products had lower average molecular weights than those obtained without catalysts. The activation energies of the cracking reactions with or without catalysts were determined. The apparent activation energy was lower in catalytic than that in thermal degradation. The cracking reaction rates were modelled and the reaction rate constant of each hydrocarbon type was calculated. The model gives a good approximation of the experimental results obtained from the degradation of LDPE waste in the presence and absence of catalysts. Under the studied parameters, liquids were formed with suitable properties for further uses (e.g. low sulphur content, low pour point).

Properties enhancement of partially biodegradable polyamide/polylactide blends through compatibilization with novel polyalkenyl-poly-maleic-anhydride-amide/imide-based additives

This work is dedicated to compatibilization process investigation between polyamide 6 and biodegradable polylactide. The process was conducted by newly developed polyalkenyl-poly-maleic-anhydride-imide/amide agents over a selected range of composition to identify morphologies and properties of these blends. The properties of resulted blends were studied by scanning electron microscopy, solvent extraction techniques, mechanical testing, Fourier transform infrared spectroscopy, and differential scanning calorimetry measurements. Results show that blending of the two polymers without compatibilizers produced multiphase blends. It was shown by scanning electron microscopy imaging that addition of prepared compatibilizers reduced a domain size of a dispersed phase and also changes in nearly co-continuous state occurred. Static and dynamic mechanical properties were improved, and especially impact strength and tensile strength were the most sensitive on the presence of compatibilizers.

Thermogravimetric analysis and pyrolysis kinetic study of Malaysian refuse derived fuels

Abstract Abstract Refuse derived fuel (RDF), containing mainly paper and plastics, is a waste material that has potential to be used for energy or fuel production. This paper reports on a thermogravimetric study and kinetic analysis of the thermal decomposition of Malaysian RDF. It was found that Malaysian RDF contained 59·8 wt-% plastics, 28·6 wt-% cardboard, 5·1 wt-% newspapers and 6·5 wt-% other materials. The plastics consisted of 64·6% polyethylene, 17·5% polypropylene, 10·1% polystyrene and 7·8% other plastics (polyethylene terephthalate, formaldehyde based resin, polyamides, acrylonitrile butadiene styrene and polycarbonate). Results obtained from sample weight loss thermograms showed significant differences in their characteristic data (degradation temperature, rate of weight loss, etc.). The kinetic parameters have been derived from non-isothermal thermogravimetric data at a temperature range from room temperature up to 650°C using a constant heating rate of 20°C min−1. The thermal degradation of...

Pressurized pyrolysis of dried distillers grains with solubles and canola seed press cake in a fixed-bed reactor.

Pressurized pyrolysis of biomasses was carried in a fixed bed reactor to obtain gases, bio-oils and chars at elevated temperatures. The products were characterized by GC-MS, FTIR, viscometer, SEM, BET and EDXRFS methods. Experiments were performed at 1, 5 and 10 bar pressure and 400, 500 and 600°C temperatures. The experimental results show that in all the experimental condition the yield of bio-oil from DDGS as higher than that of canola. Yield of non-condensable gases and chars increased, while that of liquid products decreased by pressure. Increasing pressure favoured the formation of low molecular weight gas, such as H2. Maximum surface area of chars was obtained at atmospheric pressure and the surface areas decreased rapidly with increasing pressure. GC/MS results shows that the amount of fatty acids in bio-oils was increased by increasing pressure and bio-oils showed non-Newtonian behavior. Based on EDXRFS results, bio-oils and char contained lots of elements.

Utilization of α-olefins obtained by pyrolysis of waste high density polyethylene to synthesize α-olefin-succinic-anhydride based cold flow improvers

Abstract A new route of utilization of α-olefin rich hydrocarbon fractions obtained by waste polymer pyrolysis was investigated. α-olefin-succinic-anhydride intermediate-based pour point depressant additives for diesel fuel were synthesized, in which reactions needed α-olefins were obtained by pyrolysis of waste high-density polyethylene (HDPE). Fraction of α-olefins was produced by the de-polymerization of plastic waste in a tube reactor at 500°C in the absence of catalysts and air. C 17 – 22 range of mixtures of olefins and paraffins were separated for synthesis and then, these hydrocarbons were reacted with maleic-anhydride (MA) for formation of α-olefin-succinic-anhydride intermediates. The olefin-rich hydrocarbon fraction contained approximately 60% of olefins, including 90-95% α-olefins. Other intermediates were produced in the same way by using commercial C 20 α-olefin instead of C 17 – 22 olefin mixture. The two different experimental intermediates with number average molecular weights of 1850 and 1760 g/mol were reacted with different alcohols: 1-butanol, 1-hexanol, 1-octanol, i -butanol, and c -hexanol to produce their ester derivatives. The synthesized ten experimental pour point depressants were added in different concentrations to conventional diesel fuel, which had no other additive content before. The structure and efficiency of experimental additives were followed by different standardized and non-standardized methods. Results showed that the experimental additives on the basis of the product of waste pyrolysis were able to decrease not only the pour but also the cloud point and cold filter plugging point (CFPP) of diesel fuel, whose effects could be observed even if the concentration of additives was low. Furthermore, all additives had anti-wear and anti-friction effects in diesel fuel.

Production of Acrylonitrile Butadiene Styrene/High-Density Polyethylene Composites from Waste Sources by Using Coupling Agents

A possible way of recycling plastic wastes has been investigated. Polyalkenyl-poly-maleic-anhydride derivates were synthesized and employed in ABS and HDPE blends to eliminate their immiscibility. By this way, the recycling of ABS and HDPE could be performed with improved mechanical properties of reshaped specimens.

Synthesis and Evaluation of Modified Polyethylene Wax Applied as Dispersant in Rubber Bitumen Composites

Grain rubber obtained from waste tyre has become one of the most important bitumen modifiers nowadays, but rubber precipitation from bitumen can cause problems during utilization. In our experimental work additives were synthesised as dispersant for rubber bitumen composites. Raw material was polyethylene wax (PEW) obtained from mild thermal cracking of polyethylene waste. The synthesis was a copolymerisation of olefins and maleic-anhydride. During the products evaluation the main analytical method was Fourier transform infra-red (FT-IR) spectroscopy. There were significant differences between the characteristic of raw material and synthesised products. The dispersant effect of the additives was studied in rubber-bitumen composites. All additives increased the stability of rubber-bitumen composites. From the results of the experiments it was stated that the modified polyethylene wax obtained from polyethylene waste can solve the instability problem of rubber-bitumen composites.