Waste plastics are non‐degradable constituents that can stay in the environment for centuries. Their large land space consumption is unsafe to humans and animals. Concomitantly, the continuous engineering of plastics, which causes depletion of petroleum, poses another problem since they are petroleum‐based materials. Therefore, energy recovering trough pyrolysis is an innovative and sustainable solution since it can be practiced without liberating toxic gases into the atmosphere. The most commonly used plastics, such as HDPE, LDPE (high‐ and low‐density polyethylene), PP (polypropylene), PS (polystyrene), and, to some extent, PC (polycarbonate), PVC (polyvinyl chloride), and PET (polyethylene terephthalate), are used for fuel oil recovery through this process. The oils which are generated from the wastes showed caloric values almost comparable with conventional fuels. The main aim of the present review is to highlight and summarize the trends of thermal and catalytic pyrolysis of waste plastic into valuable fuel products through manipulating the operational parameters that influence the quality or quantity of the recovered results. The properties and product distribution of the pyrolytic fuels and the depolymerization reaction mechanisms of each plastic and their byproduct composition are also discussed.
A structural investigation of liquid N-methylacetamide (NMA) is performed by x-ray scattering and density functional theory (DFT). Experimental data are analyzed to yield the total structure function SM(Q) and the pair correlation function g(r). The DFT calculations, using the standard triple zeta valence basis set augmented by a diffuse function for carbon, nitrogen and oxygen atoms, are performed on the one hand to study the structure and stability of the two possible conformers cis and trans. On the other hand, they are meant to examine some possible clusters which may describe the intermolecular arrangement in liquid NMA. Among two series of dimers and trimers associations, the spectra are particularly interpreted in terms of: Trans NMA dimers and trimers which resemble the short-range crystal structure, mixed cis and trans trimers and cis cyclic trimers. The H-bonding parameters and the intermolecular energy for each model are described.
The local order in liquid N-methylformamide has been studied by using x-ray diffraction and a density functional theory (DFT). Experimental data were analyzed to yield the total structure function SM(q) and the intermolecular pair correlation function gL(r). DFT calculations, using, namely, the standard TZV basis set, were performed to study the relative stability of the two possible isomers (cis and trans) and to examine some possible intermolecular arrangements in the liquid state. X-ray measurements can be interpreted in term of cyclic trimers of cis form molecules where each monomer can establish two N–H⋯O hydrogen bonds that are described.
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