Catalytic co-pyrolysis of waste vegetable oil and high density polyethylene for hydrocarbon fuel production

Co-pyrolysis characteristic of sugarcane waste with polyethylene terephthalate: thermal decomposition, product distribution, synergistic effect, and kinetics analysis

This work has focused on the co-pyrolysis of sugarcane waste (SW) with polyethylene terephthalate (PET) to gain insight on its thermal decomposition, product distribution, kinetics, and synergistic effect. SW and PET were blended at different ratios (100:0, 80:20, 60:40, 40:60, and 0:100), and the Coats-Redfern method was used to determine the kinetics parameters. To ascertain the synergistic effect between SW and PET, product yields and composition of chemicals were compared with the synergistic effect of the individual components of pyrolysis. The bio-oil yield was significant at 60% of PET, with a difference of 19.41 wt% compared to the theoretical value. The synergistic impact of SW:PET on ester formation and acid compound inhibition was the most dominant at the 60:40 ratio. The kinetics analysis revealed that the diffusion mechanism, power law, and order of reactions were the most probable reaction models that can explain the pyrolysis of SW, and PET, and their blends. The resultant co-pyrolysis oil contained slightly larger hydrogen and carbon contents with low oxygen, and sulphur, and nitrogen contents, which improved the quality of the bio-oil. The results of this work could be used as a guide in selecting proper reaction conditions with optimal synergy during the co-pyrolysis process.

Catalytic Copyrolysis of Used Waste Plastic and Lubricating Oil Using Cu-Modification of a Spent Fluid Catalytic Cracking Catalyst for Diesel-like Fuel Production

This work provided catalytic copyrolysis of spent lubricating oil (SLO) with waste low-density polyethylene (LDPE) using copper modification of a spent fluid catalytic cracking (sFCC) catalyst to produce diesel-like fuels in a microbatch reactor, which will lead to effective waste management, ensure sustainability, and serve as an alternative energy source. The effects of LDPE blended with SLO, temperature, reaction time, and catalyst loading using an inert nitrogen atmosphere were investigated on the yields and distributions of copyrolyzed oil, while metal modification of the sFCC was prepared and used to investigate the catalytic activity. The temperature and time of reaction played an important role in the gaseous contribution to the pyrolysis of SLO. The addition of the LDPE ratio in the catalytic copyrolysis, including Cu loading on a spent FCC template, also enhanced the acidity and was responsible for the catalytic activity, which could improve the product distribution and chemical compounds in a range of diesel-like fuels. It was shown that the pyrolyzed oil was in the range of C7-C26 with a maximum diesel-like fraction of 23.11 ± 2.88 wt % compared with the catalytic pyrolysis of SLO alone, which contained a diesel-like fraction of only 12.45 ± 1.92 wt %. It was noticed that the acid active site of the catalyst resulted in a carbon-carbon bond cleavage and further secondary reaction, leading to the conversion of the long residue fraction into a light oil product. In addition, the LDPE ratio in the catalytic copyrolysis could improve the product distribution and chemical compounds in a range of diesel-like compounds, as confirmed by the GC/MS analysis. Catalytic copyrolysis oil of the optimal process condition (0.7:0.3 mass molar of SLO/LDPE, 450 °C, 60 min, 3 wt % Cu-sFCC, and 10 wt % catalyst loading) mainly contains light hydrocarbons in the C7-C19 range. Accordingly, both the product selectivity and the conversion of the long residue to the diesel-like fraction were nearly stable (59.01 ± 1.36%) during the catalyst reusability test from one to three cycles without regeneration and significantly decreased after the fifth cycle. This is an indication that the copyrolysis enhanced the conversion of SLO by LPDE blended into smaller hydrocarbon compounds, and the catalytic activity therefore showed a major tendency toward the formation of diesel-like fractions (C8-C18).

Bio-oil and biochar from the pyrolytic conversion of biomass: A current and future perspective on the trade-off between economic, environmental, and technical indicators

Over the years, the transformation of biomass into a plethora of renewable value-added products has been identified as a promising strategy to fulfil high energy demands, lower greenhouse gas emissions, and exploit under-utilized resources. Techno-economic analysis (TEA) and life-cycle assessment (LCA) are essential to scale up this process while lowering the conversion cost. In this study, trade-offs are made between economic, environmental, and technical indicators produced from these methodologies to better evaluate the commercialization potential of biomass pyrolysis. This research emphasizes the necessity of combining LCA and TEA variables to assess the performance of the early-stage technology and associated constraints. The important findings based on the LCA analysis imply that most of the studies reported in literature focussed on the global warming potentials (GWP) under environmental category by considering greenhouse gases (GHGs) as evaluation parameter, neglecting many other important environmental indices. In addition, the upstream and downstream processes play an important role in understanding the life cycle impacts of a biomass based biorefinery. Under upstream conditions, the use of a specific type of feedstock may influence the LCA conclusions and technical priority. Under downstream conditions, the product utilization as fuels in different energy backgrounds is crucial to the overall impact potentials of the pyrolysis systems. In view of the TEA analysis, investigations towards maximizing the yield of valuable co-products would play an important role in the commercialization of pyrolysis process. However, comprehensive research to compare the conventional, advanced, and emerging approaches of biomass pyrolysis from the economic perspective is currently not available in the literature.

Probing the effect of Cu-SrO loading on catalyst supports (ZSM-5, Y-zeolite, activated carbon, Al2O3, and ZrO2) for aromatics production during catalytic co-pyrolysis of biomass and waste cooking oil

In this work, Cu-SrO bimetallic catalyst was synthesised and examined for catalytic co-pyrolysis of ironbark (IB) and waste cooking oil (WCO) using Py-GC/MS. The effect of catalyst supports (ZSM-5, Y-zeolite, activated carbon, Al₂O₃, and ZrO₂) on aromatic hydrocarbons yield was studied. The effect of catalyst support on the selectivity of gasoline (C8-C14), diesel (C15-C17), and heavy oil (>C20) components of bio-oil were studied. Non-catalytic co-pyrolysis of IB and WCO produced a heavy oil component of 58.7% (>C20). SrO initiated a ketonization reaction that converted carboxylic acids into new C-C bonds. The addition of Cu effectively promoted secondary cracking and aromatization reactions enhancing the hydrocarbon yield. Cu-SrO/ZSM-5 and Cu-SrO/Y-zeolite produced low acid content of 4.43% and 12.5%, respectively. Overall, the bimetallic catalyst Cu-SrO/ZSM-5 significantly increased the amount of C8-C14 compounds to 87.28% and reduced compounds over C20 to 1.19%.

Pyrolysis of waste oils for the production of biofuels: A critical review

The application of waste oils as pyrolysis feedstocks to produce high-grade biofuels is receiving extensive attention, which will diversify energy supplies and address environmental challenges caused by waste oils treatment and fossil fuel combustion. Waste oils are the optimal raw materials to produce biofuels due to their high hydrogen and volatile matter content. However, traditional disposal methods such as gasification, transesterification, hydrotreating, solvent extraction, and membrane technology are difficult to achieve satisfactory effects owing to shortcomings like enormous energy demand, long process time, high operational cost, and hazardous material pollution. The usage of clean and safe pyrolysis technology can break through the current predicament. The bio-oil produced by the conventional pyrolysis of waste oils has a high yield and HHV with great potential to replace fossil fuel, but contains a high acid value of about 120 mg KOH/g. Nevertheless, the application of CaO and NaOH can significantly decrease the acid value of bio-oil to close to zero. Additionally, the addition of coexisting bifunctional catalyst, SBA-15@MgO@Zn in particular, can simultaneously reduce the acid value and positively influence the yield and quality of bio-oil. Moreover, co-pyrolysis with plastic waste can effectively save energy and time, and improve bio-oil yield and quality. Consequently, this paper presents a critical and comprehensive review of the production of biofuels using conventional and advanced pyrolysis of waste oils.

Diesel Engine Performance, Emissions and Combustion Characteristics of Biodiesel and Its Blends Derived from Catalytic Pyrolysis of Waste Cooking Oil

This paper first describes a slow catalytic pyrolysis process used for synthesizing biodiesel from waste cooking oil (WCO) as a feedstock. The influence of variations in the catalyst type (sodium hydroxide and potassium hydroxide), and catalyst concentration (0.5, 1.0, 3.0, 5.0, 7.0 and 10.0% by weight) on both the pyrolysis temperature range and biodiesel yield were investigated. The results suggested that sodium hydroxide (NaOH) was more effective than potassium hydroxide (KOH) as catalysts and that the highest yield (around 70 wt.%) was observed for a NaOH concentration of about 1 wt.% The resultant pyrolysis temperature range was also significantly lower for NaOH catalyst, thus suggesting overall lower energy consumption. Compared to conventional diesel, the synthesized biodiesel exhibited relatively similar physical properties and calorific value. The biodiesel was subsequently blended with diesel fuel in different blend ratios of 0, 20, 40, 60, 80 and 100% by volume of biodiesel and were later tested in a compression ignition engine. Brake thermal efficiency and specific fuel consumption were observed to be worse with biodiesel fuel blends particularly at higher engine load above 50%. However, NOx emission generally decreased with increasing blend ratio across all engine load, with greater reduction observed at higher engine load. Similar observation can also be concluded for CO emission. In contrast, lower hydrocarbon (HC) emission from the biodiesel fuel blends was only observed for blend ratios no higher than 40%. Particulate emission from the biodiesel fuel blends did not pose an issue given its comparable smoke opacity to diesel observed during the engine test. The in-cylinder peak pressures, temperature and heat release rate of biodiesel fuel blends were lower than diesel. Overall, biodiesel fuel blends exhibited shorter ignition delays when compared to diesel fuel.

A review on advanced catalytic co-pyrolysis of biomass and hydrogen-rich feedstock: Insights into synergistic effect, catalyst development and reaction mechanism

The depletion of fossil fuel reserves and the growing demand for alternative energy sources are the main drivers of biomass and carbonaceous waste utilization. Particularly, non-edible lignocellulosic biomass is the most attractive renewable feedstock due to its abundance. Pyrolysis of biomass produces highly oxygenated compounds with oxygen content >35 wt%. The cost-effective elimination of oxygen from the pyrolysis oil is the most challenging task impeding the commercialization of biomass to biofuel processes. The effective hydrogen/carbon ratio in biomass pyrolysis oil is low (0.3), requiring external hydrogen supply to produce hydrocarbon-rich oils. Exploiting hydrogen-rich feedstock particularly, solid waste (plastic, tyre and scum) and other low-cost feedstock (lubricant oil, methane, methanol, and ethanol) offer an eco-friendly solution to upgrade the produced bio-oil. Multi-functional catalysts that are capable of cleaving oxygen, promoting hydrogen transfer and depolymerisation must be developed to produce hydrocarbon-rich oil from biomass. This review compares catalytic co-pyrolysis studies based on zeolites, mesoporous silica and metal oxides. Furthermore, a wide range of catalyst modifications and the role of each feedstock were summarised to give a complete picture of the progress made on biomass co-pyrolysis research and development.

Biomass Pyrolysis Technology by Catalytic Fast Pyrolysis, Catalytic Co-Pyrolysis and Microwave-Assisted Pyrolysis: A Review

With the aggravation of the energy crisis and environmental problems, biomass resource, as a renewable carbon resource, has received great attention. Catalytic fast pyrolysis (CFP) is a promising technology, which can convert solid biomass into high value liquid fuel, bio-char and syngas. Catalyst plays a vital role in the rapid pyrolysis, which can increase the yield and selectivity of aromatics and other products in bio-oil. In this paper, the traditional zeolite catalysts and metal modified zeolite catalysts used in CFP are summarized. The influence of the catalysts on the yield and selectivity of the product obtained from pyrolysis was discussed. The deactivation and regeneration of the catalyst were discussed. Catalytic co-pyrolysis (CCP) and microwave-assisted pyrolysis (MAP) are new technologies developed in traditional pyrolysis technology. CCP improves the problem of hydrogen deficiency in the biomass pyrolysis process and raises the yield and character of pyrolysis products, through the co-feeding of biomass and hydrogen-rich substances. The pyrolysis reactions of biomass and polymers (plastics and waste tires) in CCP were reviewed to obtain the influence of co-pyrolysis on composition and selectivity of pyrolysis products. The catalytic mechanism of the catalyst in CCP and the reaction path of the product are described, which is very important to improve the understanding of co-pyrolysis technology. In addition, the effects of biomass pretreatment, microwave adsorbent, catalyst and other reaction conditions on the pyrolysis products of MAP were reviewed, and the application of MAP in the preparation of high value-added biofuels, activated carbon and syngas was introduced.

Enhancing levoglucosan production from waste biomass pyrolysis by Fenton pretreatment

Levoglucosan is served as a significant versatile product to generate high value-added chemicals and pharmaceutical additives. Levoglucosan was predominately produced from pyrolysate of cellulose. However, the direct fast pyrolysis of waste biomass produces a small quantity of levoglucosan in comparison with the theoretical value of cellulose. This study explored Fenton pretreatment as a possible route to enhance levoglucosan yield during the fast pyrolysis of the waste corncob. The experimental results showed that different Fenton pretreated conditions and pyrolytic temperatures played vital roles in the formation of levoglucosan. The levoglucosan yield from fast pyrolysis at 500 °C of corncob pretreated by Fenton reaction of 14 mL/g H₂O₂ and 16 mM FeSO₄ was about 95% higher than that of the untreated corncob. Additionally, Fenton pretreated corncob was capable of obtaining the levoglucosan at a low pyrolytic temperature (300 °C). It was mainly attributed to the effective disrupting of biomass structures and the selective degradation of lignin and hemicellulose during pretreatment. Furthermore, the powerful removal of alkali and alkaline earth metals during Fenton pretreatment was beneficial to increasing the levoglucosan yield. These findings demonstrate that Fenton pretreatment can provide a novel effective method to enhance levoglucosan yield during biomass fast pyrolysis.

Catalytic co-pyrolysis of sugarcane bagasse and waste high-density polyethylene over faujasite-type zeolite

This study investigated the catalytic co-pyrolysis of sugarcane bagasse (SCB) and waste high-density polyethylene (HDPE) over faujasite-type zeolite derived from electric arc furnace slag (FAU-EAFS) in a fixed-bed reactor. The effects of reaction temperature, catalyst-to-feedstock ratio, and HDPE-to-SCB ratio on product fractional yields and chemical compositions were discussed. The co-pyrolysis of SCB and HDPE over FAU-EAFS increased the liquid yield and enhanced the quality of bio-oil. The maximum bio-oil (68.56 wt%) and hydrocarbon yield (74.55%) with minimum yield of oxygenated compounds (acid = 0.57% and ester = 0.67%) were achieved under the optimum experimental conditions of catalyst-to-feedstock ratio of 1:6, HDPE-to-SCB ratio of 40:60, and temperature of 500 °C. The oil produced by catalytic co-pyrolysis had higher calorific value than the oil produced by the pyrolysis of SCB alone.

Thermal and Catalytic Pyrolysis of Dodecanoic Acid on SAPO-5 and Al-MCM-41 Catalysts

In this study, dodecanoic acid was decomposed during fast pyrolysis experiments either thermally or in the presence of SAPO-5 and Al-MCM-41catalysts. The catalysts were synthesized by a hydrothermal route and subsequently characterized by XRD, TPD-NH3, and TGA, and dodecanoic acid was characterized by TGA and DSC. Analysis of the post-pyrolysis products was performed online by gas chromatography coupled with mass spectrometry (GC-MS). The results from pyrolysis at 650 °C indicated that the nature of the catalysts strongly influences the composition of the products. Linear alkenes were standard products for all pyrolysis experiments, but with Al-MCM-41, various alkene isomers with a linear and cyclic structure formed, as well as saturated and aromatic hydrocarbons. As a whole, Al-MCM-41 led to a much higher dodecanoic acid conversion and higher deoxygenation than SAPO-5. As these catalysts present small differences in strong acid site density, the difference in the global conversion of dodecanoic acid could be attributed to textural characteristics such as pore volume and surface area. In this case, the textural properties of the SAPO-5 are much lower when compared to Al-MCM-41 and, due to a lower accessibility of the reactant molecule to the acidic sites of SAPO-5, partially blocked for fatty acid molecules by the considerable amount of amorphous material, as detected by XRD.

Conversion of waste biomass and waste nitrile gloves into renewable fuel

The present study deals co-pyrolysis of neem seeds (NM) and waste nitrile gloves (WNG) in a semi-batch reactor with and without catalysts. Results confirmed that the yield of pyrolytic liquid was higher (43.52 wt% at NM: WNG ratio of 3:1) during thermal co-pyrolysis compared to that of catalytic co-pyrolysis (40.42 wt% and 37.14 wt% respectively with CaO and Al₂O₃ as catalysts). The use of catalysts increased the carbon content, acidity, and heating value and reduced the oxygen content, viscosity, and density of the pyrolytic oil. FTIR analysis suggested the presence of useful functional groups while ¹H NMR analysis confirmed high amounts of paraffin and aromatic compounds in the pyrolytic oil. GC-MS analysis of pyrolytic oil confirmed that blending of NM + WNG and use of catalysts reduced the oxygenated compounds and increased the alcohol and aldehyde thereby enhancing the fuel properties.