Pyrolysis-catalytic reforming/gasification of waste tires for production of carbon nanotubes and hydrogen

The production of high-value carbon nanotubes and hydrogen from the two-stage pyrolysis catalytic-steam reforming/gasification of waste tires have been investigated. The catalysts used were Co/Al₂ O₃ , Cu/Al₂ O₃ , Fe/Al₂ O₃ and Ni/Al₂ O₃ . The pyrolysis temperature and catalyst temperature were 600 °C and 800 °C, respectively. The fresh catalysts were analysed by temperature programmed reduction and X-ray diffraction. The product gases, including hydrogen were analysed by gas chromatography and the carbon nanotubes characterized by scanning and transmission electron microscopy and Raman spectrometry. The results showed that the Ni/Al₂ O₃ catalyst produced high quality multiwalled carbon nanotubes along with the highest H₂ yield of 18.14 mmol g⁻¹ tire, compared with the other catalysts, while the Co/Al₂ O₃ and Cu/Al₂ O₃ catalysts produced lower hydrogen yield, which is suggested to be associated with the formation of amorphous type carbons on the surface of the Co/Al₂ O₃ and Cu/Al₂ O₃ catalyst

Structural change of fluid catalytic cracking catalysts study incorporate with coke characterization formed in heavy oil volatilization/decomposition

Porous structure change of catalyst and coke formation from feedstock on fluid catalytic cracking (FCC) catalyst have studied by a more comprehensive set of analyses, include 2D, 3D analyses incorporate with carbon/coke characterization teniques. Carbon/coke formed from a heavy oil volatilization/decomposition with different oil-to-FCC catalyst ratio (1:3, 1:2, 1:1, 2:1 and 3:1) to simulate the aging of FCC catalyst in a continuous oil refinery. Carbon/coke was formed for all used FCC catalyst samples that is generally increases with the increase of oil-to-FCC catalyst ratio. Coke formation has been correlated with the porosity change of the FCC catalyst, that more carbon/coke formed on the FCC catalyst due to the increment of oil-to-FCC catalyst ratio leads to the decrease of total pore volume and surface area. Zeolite is evenly distributed from the FCC catalyst particle centre to the exterior for all pristine and used FCC catalyst particles. The interior porous structure of single FCC catalyst particle is not affected by the coking. However, the exterior porous structure is completely disappear for all used FCC catalyst, that could cause by porous frame collapse and the coking clog the surface pores. The more comprehensive study of the structural change incorporate with the carbon/coke characterisation, which helps to understand the progressive degredation of FCC catalyst caused by porous structure change more in depth. Figure 1 is an example of 3 D tomogram and the radial distribution profiles of pristine FCC catalyst. Please click Additional Files below to see the full abstract

Insights into in-situ catalytic degradation of plastic wastes over zeolite-based catalyst from perspective of three-dimensional pore structure evolution

Acknowledgements The authors are grateful for financial supports provided by the Royal Society of Chemistry Enablement Grant (E21-5819318767) and Royal Society of Chemistry Mobility Grant (M19-2899), National Natural Science Foundation of China (No. 51906110), the Natural Science Foundation of Jiangsu province, China (No. BK20190465). The authors gratefully acknowledge financial support from China Scholarship Council.Peer reviewedPublisher PD

Pyrolysis-catalysis of waste plastic using a nickel-stainless steel mesh catalyst for high value carbon products.

A stainless steel mesh loaded with nickel catalyst was produced and used for the pyrolysis-catalysis of waste high density polyethylene with the aim of producing high value carbon products, including carbon nanotubes. The catalysis temperature and plastic to catalyst ratio were investigated to determine the influence on the formation of different types of carbon deposited on the nickel-stainless steel mesh catalyst. Increasing temperature from 700 to 900 °C resulted in an increase in the carbon deposited on the nickel loaded stainless steel mesh catalyst from 32.5 wt.% to 38.0 wt.%. The increase of sample to catalyst ratio reduced the amount of carbon deposited on the mesh catalyst in terms of g carbon g(-1) plastic. The carbons were found to be largely composed of filamentous carbons, with negligible disordered (amorphous) carbons. Transmission electron microscopy analysis of the filamentous carbons revealed them to be composed of a large proportion (estimated at ∼40%) multi-walled carbon nanotubes. The optimum process conditions for carbon nanotube production, in terms of yield and graphitic nature, determined by Raman spectroscopy, was catalysis temperature of 800 °C and plastic to catalyst ratio of 1:2 where a mass of 334 mg of filamentous/multi-walled carbon nanotubes g(-1) plastic was produced

Microwave-assisted Hydrothermal Carbonization for Solid Biofuel Application : A Brief Review

Acknowledgment The authors would like to acknowledge Institute of Sustainable En- ergy of University Tenaga Nasional for supporting and funding the work through the AAIBE Chair of Renewable Energy research fund-Grant no: 201901KETTHA.Peer reviewedPublisher PD

Recent advances in acoustic diagnostics for electrochemical power systems

Acknowledgments The authors would like to gratefully acknowledge the EPSRC for supporting the electrochemical research in the Electrochemical Innovation Lab (EP/R020973/1; EP/R023581/1; EP/N032888/1; EP/R023581/1; EP/P009050/1; EP/M014371/1; EP/M009394; EP/L015749/1; EP/K038656/1) and Innovate UK for funding the VALUABLE project (Grant No. 104182). The authors would also like to acknowledge the Royal Academy of Engineering for funding Robinson and Shearing through ICRF1718\1\34 and CiET1718 respectively and the Faraday Institution (EP/S00353/1, Grant Nos. FIRG003, FIRG014). The authors also acknowledge the STFC for supporting Shearing and Brett (ST/K00171X/1) and ACEA for supporting ongoing research at the EIL. Support from the National Measurement System of the UK Department for Business, Energy and Industrial Strategy is also gratefully acknowledged.Peer reviewedPublisher PD

Carbon nanotubes and hydrogen production from the pyrolysis catalysis or catalytic-steam reforming of waste tyres

A range of process conditions have been investigated to maximise the production of carbon nanotubes (CNTs) and/or hydrogen from waste tyres. A two-stage pyrolysis-catalytic reactor system was used and the influence of catalyst temperature (700, 800 and 900 °C), tyre: catalyst ratio (1:0.5, 1:1 and 1:2) and steam input (water injection 0, 2 and 5 ml h−1) to the second catalyst stage were investigated. The catalyst used was a Ni/Al2O3 catalyst prepared by a wetness impregnation technique. Carbon was deposited on the catalyst surface during pyrolysis-catalysis increasing with increasing catalyst temperature and also increasing as the tyre: catalyst ratio was raised. Examination of the carbon showed it to be composed of largely filamentous type carbons, producing 253.7 mg g−1 tyre of filamentous carbons at a tyre: catalyst ratio of 1:1 and catalyst temperature of 900 °C. A significant proportion of the deposited filamentous carbons were multi-walled carbon nanotubes as shown by transmission electron microscopy characterisation. The introduction of steam to the process enhanced hydrogen production, producing a maximum of 34.69 mmol g−1 tyre at a water injection rate of 5 ml h−1

Development of Ni- and Fe- based catalysts with different metal particle sizes for the production of carbon nanotubes and hydrogen from thermo-chemical conversion of waste plastics

Co-production of valuable hydrogen and carbon nanotubes (CNTs) has obtained growing interest for the management of waste plastics through thermo-chemical conversion technology. Catalyst development is one of the key factors for this process to improve hydrogen production and the quality of CNTs. In this work, Ni/SiO2 and Fe/SiO2 catalysts with different metal particle sizes were investigated in relation to their performance on the production of hydrogen and CNTs from catalytic gasification of waste polypropylene, using a two-stage fixed-bed reaction system. The influences of the type of metals and the crystal size of metal particles on product yields and the production of CNTs in terms of morphology have been studied using a range of techniques; gas chromatography (GC); X-ray diffraction (XRD); temperature programme oxidation (TPO); scanning electron microscopy (SEM); transmission electron microscopy (TEM) etc. The results show that the Fe-based catalysts, in particular with large particle size (∼80 nm), produced the highest yield of hydrogen (∼25.60 mmol H2 g−1 plastic) and the highest yield of carbons (29 wt.%), as well as the largest fraction of graphite carbons (as obtained from TPO analysis of the reacted catalyst). Both Fe- and Ni-based catalysts with larger metal particles produced higher yield of hydrogen compared with the catalysts with smaller metal particles, respectively. Furthermore, the CNTs formed using the Ni/SiO2-S catalyst (with the smallest metal particles around 8 nm) produced large amount of amorphous carbons, which are undesirable for the process of CNTs production

Hydrogen and Carbon Nano-Materials from the Pyrolysis-Catalysis of Wastes

In this work, a two-stage fixed-bed reaction system was used for the production of carbon nanotubes along with hydrogen production from waste tyres and plastics from a pyrolysis-catalysis/catalytic-reforming process. The preliminary investigations concerned different metal catalysts (Ni/Al2O3, Co/Al2O3/ Fe/Al2O3 and Cu/Al2O3), which were investigated to determine the effects on carbon nanotube and hydrogen production by pyrolysis-catalysis of waste truck tyres. The results showed catalyst addition in the pyrolysis-catalysis of waste tyre process can increase hydrogen production. The Ni/Al2O3 catalyst gave the highest hydrogen production at 18.14 mmol g-1 along with production of relatively high quality carbon nanotubes which were homogenous. The influence of catalyst support was investigated with different SiO2:Al2O3 ratios (3:5, 1:1, 3:2, 2:1) with nickel. The results showed that the Ni-based SiO2:Al2O3 supported catalyst at a 1:1 ratio at 900 oC with sample to catalyst ratios at 1:2 gave the highest hydrogen production at 27.41 mmol g-1, and the 1:1 ratio gave the highest filamentous carbon production at 201.5 mg g-1. The influence of process parameters on hydrogen and CNTs production were investigated with the Ni/Al2O3 catalyst. Hydrogen production reached the highest amount which was 27.41 mmol g-1 at 900 oC with sample to catalyst ratio was 1:2. The highest filamentous carbon production was produced with the sample to catalyst ratio at 1:1 at 900 oC catalyst temperature. The water injection rates were also investigated, the results showed that water introduction inhibited filamentous carbon production but increased the hydrogen production. An in-depth study to better understand the process involved investigation of three different tyre rubbers and five tyre pyrolysis oil model compounds to understand the mechanism of carbon nanotubes formation in waste tyres by the pyrolysis-catalysis process. The results showed that natural rubber which is the main component of tyre samples which used for this thesis, dominated hydrogen production at 25 mmol g-1 and SBR gave the highest carbon formation which was 40 wt. %. The aliphatic model compounds (hexadecane and decane) favoured gaseous hydrocarbons formation instead of solid carbon formation, but the aromatic model compounds (styrene, naphthalene and phenanthrene) favour solid carbon formation where the majority of carbon formation was filamentous carbon. The study was extended to investigate waste plastics and different types of waste plastic feedstock used in the pyrolysis catalysis/catalytic reforming process to produce hydrogen and carbon nanotubes. As carbon nanotubes separation from the catalyst is a challenge for this project, the nickel metal catalyst was loaded on stainless steel mesh and applied in the high-density polyethylene pyrolysis-catalysis process. The benefit of this catalyst has been shown in that the carbon formation could be easily separated by physical shaking from the stainless steel-nickel mesh catalyst. However, further investigation on waste plastics was concentrated on hydrogen production and where carbon nanotubes were the by-product from the process. Fe-based and Ni-based catalysts as bimetallic catalysts supported by MCM-41 with different Fe:Ni ratios were investigated using simulated mixed waste plastics. A synergistic effect of the iron and nickel was observed, particularly for the (10:10) Fe/Ni/MCM-41 catalyst where the highest gas yield (95 wt.%) and highest H2 production (46.1 mmol g-1plastic have been achieved. Along with lowest carbon deposition which was 6 wt.% with carbon nanotubes formation. Seven real world waste plastics were used to produce hydrogen and carbon nanotubes in the presence of a Fe:Ni at 10:10 ratio catalyst with an MCM-41 support. The results showed that the agricultural waste plastic gave the highest hydrogen production that was 55.99 mmol g-1 with carbon nanotubes formation. The calorific values of the produced gases from different plastic samples were in the range of 12.13 - 24.06 MJ m-3, which could provide the process fuel that shows the possibility to apply the technology for further larger scale of research