Catalytic pyrolysis of HDPE in continuous mode over zeolite catalysts in a conical spouted bed reactor

A study has been carried out using HZSM-5, HY and Hβ zeolite-based catalysts in the pyrolysis of high density polyethylene (HDPE) continuously fed into a conical spouted bed reactor (CSBR) at 500 °C and atmospheric pressure, with the aim being to assess the yields and composition of the main products (both light olefins and automotive fuel hydrocarbons). Product streams have been grouped into seven lumps: light olefins (C₂–C₄) and light alkanes (<C₄) in the gas fraction, the liquid fraction consisting of three lumps (non-aromatic C₅–C₁₁ compounds, single-ring aromatics and C₁₁₊ hydrocarbons), wax and coke. The results are compared with those already obtained in thermal pyrolysis in a CSBR and with those obtained in the literature using catalysts in bubbling fluidized beds. HZSM-5 zeolite-based catalyst is very selective to light olefins, ≈58 wt% once equilibrated; whereas high yields of non-aromatic C₅–C₁₁ products (around 45 wt%) are obtained with Hβ and HY zeolite-based catalysts. Wax yield increases as reactions proceed, especially with HY and Hβ zeolite-based catalysts, due to catalyst deactivation by coke formation. Product distribution with the different catalysts and their evolution throughout continuous operation by feeding HDPE is explained according to the different properties of the zeolites used.     

Effects of the types of zeolites on catalytic upgrading of pyrolysis wax oil

Because zeolites play an important role in an upgrading catalyst for heavy hydrocarbons in industrial refinery processes, the effects of the zeolite type on the upgrading of pyrolysis wax oil are investigated in this study. Raw pyrolysis wax oil was obtained from the pyrolysis of municipal plastic wastes in a commercial rotary kiln pyrolysis plant (Dongmyong RPF Co.). The catalystic experiments are performed for the three different types of commercial zeolites with different physicochemical properties in a continuous fixed bed reactor at 450 °C for 1 h as a MAT(micro-activity test) method: HZSM-5 (pure), zeolite Y (HY; pure or including 20% clay) and mordenite (HM; including 20% clay or alumina) catalysts. The highest conversion of pyrolysis wax oil into light hydrocarbons such as gas products and gasoline-range hydrocarbons is obtained for the HZSM-5 catalyst among them, and the composition of liquid products is found to become in the main aromatic components due to a shape selectivity. For the case of zeolite Y(HY), medium activity and the highest fraction of branched hydrocarbons with a high octane number, as well as a high fraction of aromatic products are shown. However, the mordenite (HM) with one-dimensional pore structure shows the lowest conversion of pyrolysis wax oil into light hydrocarbons and a very high fraction of paraffin product in the liquid product like the characteristics of raw pyrolysis wax oil.     

Scrap Tires Pyrolysis: Product Yields,Properties and Chemical Compositions of Pyrolytic Oil

This investigation involves an experimental study on the pyrolysis of scrap tires under different operating conditions such as feedstock size and pyrolysis temperature by highlighting the properties of the whole liquid products generated during each thermal degradation process. The complete conversion temperature for the pyrolysis of used tires was close to 500?550°C. The characteristics of liquid fraction were determined by elemental analysis, chromatographic and spectroscopic techniques and distillation data. All the obtained atomic ratios are around 1,4 which is significant that such pyrolytic liquids are a mixture of aliphatic and aromatic compounds derived from polymeric materials. Analysis of the pyrolytic oil (pyro-oil) by chromatographic analysis showed that it was a complex mixture of organic compounds C₅?C₂₆, aromatics and a large proportion of light hydrocarbons that can be used as liquid fuels. Furthermore, the comparison distillation data indicates that more than 40% of such pyrolytic oil fraction with the boiling point range between 180?360°C is specified for diesel. It is noted that the viscosity decreases obviously from 4.87 to 1.79 with the increase in temperature.     

Gas Evolution from the Pyrolysis of Jordan Oil Shale in A Fixed-bed Reactor

Jordan oil shale from El-Lajjun deposit was pyrolysed in a fixed-bed pyrolysis reactor and the influence of the pyrolysis temperature between 400 to 620°C and the influence of the pyrolysis atmosphere using nitrogen and nitrogen/steam on the product yield and gas composition were investigated. The gases analysed were H₂, CO, CO₂ and hydrocarbons from C₁ to C₄. The results showed for both nitrogen and nitrogen/steam that increase the pyrolysis bed temperature from 400 to 520°C resulted in a significant increase in the oil yield, after which temperature the oil yield decreased. The alkene/alkane ratio including ethene/ethane, propene/propane, and butene/butane ratios, can be used as an indication of pyrolysis temperature and the magnitude of cracking reactions. Increasing alkene/alkane ratio occurring with increasing pyrolysis temperature. The alkene/alkane ratio for nitrogen/steam pyrolysis atmosphere was lower than the one found under nitrogen atmosphere. This revised version was published online in July 2006 with corrections to the Cover Date.     

Gas-liquid chromatographic determination of the gaseous products of the two-stage pyrolysis of heavy oils

The two-stage pyrolysis of fuel oil and vacuum residues separated from Egyptian crude oil have been carried out using a batch-type reactor technique. In the first stage, feedstocks undergo catalytic cracking in the presence of platinum as a catalyst at temperatures ranging between 380 and 460 °C and 440 and 520 °C for fuel oil and vacuum residues, respectively. Products are carried by argon gas for subsequent pyrolysis in the second stage at temperatures ranging between 700 and 820 °C and 700 and 800 °C for fuel oil and vacuum residues, respectively. The gas yields are about 94.1 and 82.0 wt% of the total products. The gases comprise saturated (C₁----C₅) and unsaturated hydrocarbons (ethylene, propylene, and butenes). By using platinum wire in the pyrolysis of fuel oil, the ethylene yield increases slightly as the temperature of the first stage increases, while it remains almost unchanged in the pyrolysis of vacuum residue. On the other hand, the propylene yield decreases slightly as the temperature of the first stage increases in the two feedstocks. By using a platinum sheet, the ethylene yield is doubled under the same conditions and increases slightly with an increase of temperature in the second stage. On the other hand, the propylene yield varies inversely with the temperature of the second stage by using platinum, whether as wire or sheet, although the yield is higher when platinum sheet is used under the same conditions.     

Light olefins and light oil production from catalytic pyrolysis of waste tire

This paper investigates the catalytic activity of MCM-41 synthesized via silatrane route and Ru/MCM-41 in waste tire pyrolysis. The experimental results showed that the presence of catalysts strongly influenced the yield and nature of products. Namely, the gas yield increased at the expense of liquid yield. In addition, a considerable high yield of light olefins, 4 times higher than non-catalytic pyrolysis, can be achieved for Ru/MCM-41 catalyst. Furthermore, the uses of catalysts produced much lighter oil and there was a drastic increase in the concentration of single ring aromatics in accordance to a reduction in polycyclic aromatic compounds in the derived oils. Ru/MCM-41 produced the lightest oil and the oil has the highest concentration of mono-aromatics. The high activity of catalysts, particularly Ru/MCM-41 was discussed in relation with the catalyst characterization results obtained from various techniques including TPD-NH₃, H₂-chemisorption, XRD, N₂-adsorption/desorption analysis, and TPO.     

Screening acidic zeolites for catalytic fast pyrolysis of biomass and its components

Zeolites have been shown to effectively promote cracking reactions during pyrolysis resulting in highly deoxygenated and hydrocarbon-rich compounds and stable pyrolysis oil product. Py/GC-MS was employed to study the catalytic fast pyrolysis of lignocellulosic biomass samples comprising oak, corn cob, corn stover, and switchgrass, as well as the fractional components of biomass, i.e., cellulose, hemicellulose, and lignin. Quantitative values of condensable vapors and relative compositions of the pyrolytic products including non-condensable gases (NCG's) and solid residues are presented to show how reaction products are affected by catalyst choice. While all catalysts decreased the oxygen-containing products in the condensable vapors, H-ZSM-5 was most effective at producing aromatic hydrocarbons from the pyrolytic vapors. We demonstrated how the Si/Al ratio of the catalysts plays a role in the deoxygenation of the vapors towards the pathway to aromatic hydrocarbons.     

Catalysis Meets Nonthermal Separation for the Production of (Alkyl)phenols and Hydrocarbons from Pyrolysis Oil

A simple and efficient hydrodeoxygenation strategy is described to selectively generate and separate high‐value alkylphenols from pyrolysis bio‐oil, produced directly from lignocellulosic biomass. The overall process is efficient and only requires low pressures of hydrogen gas (5 bar). Initially, an investigation using model compounds indicates that MoC_x /C is a promising catalyst for targeted hydrodeoxygenation, enabling selective retention of the desired Ar−OH substituents. By applying this procedure to pyrolysis bio‐oil, the primary products (phenol/4‐alkylphenols and hydrocarbons) are easily separable from each other by short‐path column chromatography, serving as potential valuable feedstocks for industry. The strategy requires no prior fractionation of the lignocellulosic biomass, no further synthetic steps, and no input of additional (e.g., petrochemical) platform molecules.     

Catalytic thermal decomposition of polyamides and polyurethanes mixed with acidic zeolites

The purpose of this work was to examine the pyrolysis products derived from zeolite–polyamide and zeolite–polyurethane mixtures prepared in different ratios in order to elucidate the chemical reactions taking place under pyrolysis of these polymers in the presence of acidic Y zeolites (ultra stabilized HY (HUSY) and NH₄NaY). Therefore 5:1, 3:1, and 1:1 ratios of zeolite and nitrogen-containing polymer (polyamides and polyurethanes) mixtures were pyrolysed at 500 °C in a micro-pyrolyser on-line coupled with GC/MS. The products and product distribution of zeolite–polymer mixtures indicate that the amount of catalysts significantly affects the pyrolysis product distribution. In case of zeolite–PA-6,6 1:1 mixtures hexanedinitrile is the main pyrolysis product indicating that the thermal decomposition of PA-6,6 via cis-elimination is enhanced. Main pyrolysis products of zeolite–PA-6 mixtures of 1:1 ratio are dihydro-azepine isomers that are the dehydrated derivatives of ɛ-caprolactam. Pyrolysis of 1:1 zeolite–PA-12 mixtures leads to the promoted formation of dehydrated cyclic monomer isomers (azacyclotrideca-dienes). For zeolite–PUR 1:1 mixtures it was concluded that MDI decomposition to N-containing aromatics is enhanced, while the polyester and polyether segments degrade to monomer type products and to aromatics. For all zeolite–polymer mixtures increasing ratio of catalysts leads to increased amount of aromatics (benzene and naphthalene compounds) and light unsaturated hydrocarbons, while the amount of main products of 1:1 mixtures decreases.     

Pyrolytic and catalytic conversion of rape oil into aromatic and aliphatic fractions in a fixed bed reactor on Al2O3 and Al2O3/B2O3 catalysts

In the, at present, unstable fuel market, much attention is devoted to alternative technologies for fuel production and development of alternative products of the petrochemical industry. One of the prospective sources of fuel and alternative petrochemical products is biomass, and the use of oil plants is one of the possibilities. This paper reports on a possible conversion of rapeseed oil produced in Poland into intermediate hydrocarbon fractions by pyrolysis combined with parallel catalytic conversion. The products were analysed by gas chromatography coupled with a mass detector. The process was performed in a fixed-bed reactor and was monitored by FTIR and ¹H NMR. Depending on the catalysts applied, the products contained: water, carbon oxides, hydrogen, aliphatic or aromatic hydrocarbons accompanied by some amount of C2-C5 hydrocarbons formed during the cracking process. Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May 2008.     

Study of the pyrolysis of municipal solid waste for the production of valuable products

To obtain information on the potential of thermal conversion (pyrolysis) of municipal solid waste (MSW), a thermogravimetric study (TGA) is performed in a stream of nitrogen. Based on TGA results, pyrolysis experiments are carried out in a semi-batch reactor under inert nitrogen atmosphere. Slow pyrolysis is performed up to 550 °C (heating rate of 4 °C/min). Fast pyrolysis is performed at 450, 480, 510 and 550 °C and different input transfer rates (12 or 24 g material/min). The pyrolysis products are studied on composition and yield/distribution and investigated for their use as valuable product.The liquid obtained by slow pyrolysis separates spontaneously in a water rich product and an oily product. For all fast pyrolysis conditions, a viscous, brown oil which contains a poly(ethylene-co-propylene) wax is obtained. Composition analyses by GC/MS of the oil products (slow/fast pyrolysis) show that aliphatic hydrocarbons are the major compounds. The pyrolysis oils have high calorific value (between 35 and 44 MJ/kg), low wt% of water (around 6 wt%) and a low O/C value (between 0.2 and 0.3). The presence of waxy material is probably due to incomplete breakdown of poly(ethylene-co-propylene) present in MSW under study. The optimal pyrolysis conditions, regarding to oil yield, fuel properties, and wax yield is fast pyrolysis at 510 °C with 24 g material/min input transfer rate. The fast pyrolysis gases contain mainly hydrocarbons and have an averaged LHV around 20 MJ/Nm³. ICP-AES analyses of pyrolysis products reveal that almost none of the metals present in MSW are distributed within the liquid fractions.     

Thermal degradation of polyethylene and polystyrene from the packaging industry over different catalysts into fuel-like feed stocks

Thermal degradation of waste polymers was carried out as a suitable technique for converting plastic polymers into liquid hydrocarbons, which could be used as feed stock materials. The catalytic degradation of waste plastics (polyethylene and polystyrene) was investigated in a batch reactor over different catalysts (FCC, ZSM-5 and clinoptillolite). The effects of catalysts and their average grain size on the properties of main degradation products (gases, gasoline, diesel oil) are discussed. The temperature range of 410-450 °C was used in the process. Both equilibrium FCC catalyst and natural clinoptilolite zeolite catalyst had good catalytic activity to produce light hydrocarbon liquids, and ZSM-5 catalyst produced the highest amount of gaseous products. Gases and liquids formed in cracking reactions were analyzed by gas chromatography. The liquid products consisted of a wide spectrum of hydrocarbons distributed within the C₅-C₂₈ carbon number range depending on the cracking parameters. The composition of hydrocarbons had linear non-branched structure in case of polyethylene, while from polystyrene more aromatics (ethyl-benzene, styrene, toluene, and benzene) were produced. The yields of volatile products increased with increasing degradation temperature. The olefin content of liquids was measured with an infrared technique and an olefin concentration of 50-60% was observed. The concentration of unsaturated compounds increased with decreasing temperature, and in the presence of catalysts. The activation energies were calculated on the basis of the composition of volatile products. The apparent activation energies were decreased by catalysts and catalyst caused both carbon-chain and double bond isomerisation.     

Comparison of catalytic pyrolysis of biomass with MCM-41 and CaO catalysts by using TGA–FTIR analysis

Pyrolysis of corncob with and without catalyst was investigated using thermogravimetry analyzer coupled with Fourier transform infrared spectroscopy (TGA–FTIR). The effects of two completely different catalysts, acid catalyst (MCM-41) and base catalyst (CaO), on the formation characteristics and composition of pyrolysis vapor were studied. The results show that these two catalysts give different product distributions. For catalytic run with MCM-41, the molality of carbonyl compounds decreases 10.2%, while that of phenols, hydrocarbons and CH₄ increases 15.32%, 4.29% and 10.16% compared with non-catalytic run, respectively. The increase of phenols exhibits in a wide temperature range from about 295 °C to 790 °C in the catalytic run with MCM-41 catalyst. However, the use of CaO in pyrolysis of corncob leads to a huge change of product distribution. The molality of acids decreases 75.88%, while the molality of hydrocarbons and CH₄ increases 19.83% and 51.05% compared with non-catalytic run, respectively. CaO is very effective in deacidification and the conversion of acids promotes the formation of hydrocarbons and CH₄. Catalytic pyrolysis of corncob with CaO shows two main weight-loss stages. The first stage is from 235 °C to 310 °C with a weight loss of 31%. The second stage is from 650 °C to 800 °C with a weight loss of 21%.     

Pyrolysis of liquid hexadecane with selective microwave heating of the catalyst

The pyrolysis of liquid n-hexadecane was studied on various catalysts with selective microwave (MW) heating of a catalyst possessing much greater microwave absorption capacity than the long-chain hydrocarbon studied. This method permits rapid heating of the catalyst to temperatures much higher than 400 °C, leading to reflux of the liquid substrate, movement of the catalyst granules within the substrate, and chemical transformations (cracking) of hexadecane. High pyrolysis selectivity relative to α-olefins was found on various catalysts such as magnetic microspheres (coal combustion ash), Al₂O₃/Al, and Pd/KTP (glass fiber). This behavior may be attributed to tempering of the primary products in the bulk of the liquid reagent. Furthermore, MW pyrolysis on magnetic microspheres was found to be accompanied by formation of rather thick carbon microfibers with diameter 300–500 nm.     

应用TG-FTIR技术研究黄土庙煤催化热解特性

用浸渍法制备过渡金属氧化物担载型催化剂MO_x/USY(M=Co、Mo、Co-Mo),用热重红外联用技术考察了MO_x/USY催化剂对黄土庙(HTM)煤热解失重特性和热解产物生成规律的影响。热重实验结果表明,MO_x/USY催化剂可使HTM煤热解的二次脱气条件更为温和,热解峰温分别提前14、23和9℃。动力学分析结果表明,MO_x/USY催化剂可降低HTM煤样热解的活化能。FT-IR研究表明,MO_x/USY催化剂可有效改善HTM煤热解产物的组成和分布,CoO_x/USY催化剂能显著提高HTM煤热解产物中高热值气体(CO、CH₄)和轻质芳烃以及脂肪烃类化合物的含量;MoO_x/USY催化剂没有明显改善HTM煤热解产物组成和分布;MoO_x-CoO_x/USY催化剂可促进CO、CH₄、轻质芳烃和脂肪烃类化合物的生成,却使热解产物的生成向高温区移动,说明USY负载的不同过渡金属氧化物对煤样热解行为和热解产物有较大影响。     

Characterization of the different fractions obtained from the pyrolysis of rope industry waste

A study of the possibilities of pyrolysis for recovering wastes of the rope's industry has been carried out. The pyrolysis of this lignocellulosic residue started at 250 °C, with the main region of decomposition occurring at temperatures between 300 and 350 °C. As the reaction temperature increased, the yields of pyrolyzed gas and oil increased, yielding 22 wt.% of a carbonaceous residue, 50 wt.% tars and a gas fraction at 800 °C. The chemical composition and textural characterization of the chars obtained at various temperatures confirmed that even if most decomposition occurs at 400 °C, there are some pyrolytic reactions still going on above 550 °C. The different pyrolysis fractions were analyzed by GC–MS; the produced oil was rich in hydrocarbons and alcohols. On the other hand, the gas fraction is mainly composed of CO₂, CO and CH₄. Finally, the carbonaceous solid residue (char) displayed porous features, with a more developed porous structure as the pyrolysis temperature increased.     

Effect of catalysts on the yield of products formed in biomass gasification

The effect of catalysts on the yield of products formed in thermal treatment of wood in the filtration combustion mode was experimentally studied. Natural zeolite of TsPS brand and K₂CO₃ were used as catalysts. The products were analyzed and the results were compared with those for noncatalytic systems. With the catalysts, the combustion temperature decreased by 100–200°C. The yield of liquid products formed in wood pyrolysis decreased with increasing amount of a catalyst in the mixture, and the appearance of unburned carbon on catalyst particles was also observed.     

Morphology-Directed Selective Production of Ethylene or Ethane from CO2 on a Cu Mesopore Electrode

The electrocatalytic conversion of CO₂ to value-added hydrocarbons is receiving significant attention as a promising way to close the broken carbon-cycle. While most metal catalysts produce C₁ species, such as carbon monoxide and formate, the production of various hydrocarbons and alcohols comprising more than two carbons has been achieved using copper (Cu)-based catalysts only. Methods for producing specific C₂ reduction outcomes with high selectivity, however, are not available thus far. Herein, the morphological effect of a Cu mesopore electrode on the selective production of C₂ products, ethylene or ethane, is presented. Cu mesopore electrodes with precisely controlled pore widths and depths were prepared by using a thermal deposition process on anodized aluminum oxide. With this simple synthesis method, we demonstrated that C₂ chemical selectivity can be tuned by systematically altering the morphology. Supported by computational simulations, we proved that nanomorphology can change the local pH and, additionally, retention time of key intermediates by confining the chemicals inside the pores.     

Molybdovanadophosphoric Acid Catalyzed Oxidation of Hydrocarbons by H2O2 to Oxygenates

Heteropoly acids of the general formula H_3+x[PMo_12-xV_xO₄₀] (where x = 1,2,3) catalyzed the oxidation of aromatic hydrocarbons at 65°C with H₂O₂ to give oxygenated products. Among the catalysts, H₄[PMo₁₁VO₄₀] was found to be a more active catalyst and its activities have been reported in the oxidation of cyclohexane, methyl cyclohexane, naphthalene, 1-methyl naphthalene and biphenyl.     

Morphology‐Directed Selective Production of Ethylene or Ethane from CO2 on a Cu Mesopore Electrode

The electrocatalytic conversion of CO₂ to value‐added hydrocarbons is receiving significant attention as a promising way to close the broken carbon‐cycle. While most metal catalysts produce C₁ species, such as carbon monoxide and formate, the production of various hydrocarbons and alcohols comprising more than two carbons has been achieved using copper (Cu)‐based catalysts only. Methods for producing specific C₂ reduction outcomes with high selectivity, however, are not available thus far. Herein, the morphological effect of a Cu mesopore electrode on the selective production of C₂ products, ethylene or ethane, is presented. Cu mesopore electrodes with precisely controlled pore widths and depths were prepared by using a thermal deposition process on anodized aluminum oxide. With this simple synthesis method, we demonstrated that C₂ chemical selectivity can be tuned by systematically altering the morphology. Supported by computational simulations, we proved that nanomorphology can change the local pH and, additionally, retention time of key intermediates by confining the chemicals inside the pores.