Fe-POM/attapulgite composite materials: Efficient catalysts for plastic pyrolysis.

This article describes the catalytic cracking of low-density polyethylene over attapulgite clay and iron substituted tungstophosphate/attapulgite clay (Fe-POM/attapulgite) composite materials to evaluate their suitability and performance for recycling of plastic waste into liquid fuel. The prepared catalysts enhanced the yield of liquid fuel (hydrocarbons) produced in cracking process. A maximum yield of 82% liquid oil fraction with a negligible amount of coke was obtained for 50% Fe-POM/attapulgite composite. Whereas, only 68% liquid oil fractions with a large amount of solid black residue was produced in case of non-catalytic pyrolysis. Moreover, Fe-POM/attapulgite clay composites showed higher selectivity towards lower hydrocarbons (C5-C12) with aliphatic hydrocarbons as major fractions. These synthesised composite catalysts significantly lowered the pyrolysis temperature from 375°C to 310°C. Hence, recovery of valuable fuel oil from polyethylene using these synthesised catalysts suggested their applicability for energy production from plastic waste at industrial level as well as for effective environment pollution control.

Method development and evaluation of pyrolysis oils from mixed waste plastic by GC-VUV.

The conversion of waste streams into a useable material through a recycling process is a hot topic. Waste streams can originate from domestic and industrial sources and range from plastic waste to medical waste to various industrial waste streams, both solid and liquid. In addition to waste circularity, circularity for bio-based waste streams and renewable sources are also being investigated. To simplify this complexity, this article presents a case study evaluating the output from the feedstock recycling of plastic waste originating from municipal solid waste. Plastic waste entering the environment is undesired, and many initiatives are working towards a plastics circular economy. Once disposed of, ideally, plastic waste should be either re-used or recycled in order to avoid incineration or disposal in landfills. Recycling waste plastic can occur either via mechanical recycling or feedstock (chemical) recycling, where feedstock recycling can occur for example, through gasification or pyrolysis technologies. This article will focus only on the oils obtained from the pyrolysis of mixed waste plastic. The output from pyrolysis has a different composition than traditional fossil-based hydrocarbon streams, and therefore, must be evaluated to correctly process as feedstock. The authors have previously shown that gas chromatography coupled to vacuum ultraviolet detection (GC-VUV) provides accurate identification and quantification of the hydrocarbon composition (paraffins, isoparaffins, olefins, naphthenes, and aromatics - PIONA) of fossil-based liquid hydrocarbon streams.1 Therefore, GC-VUV was evaluated for analysis of the pyrolysis oils from plastic waste. Using an in-house modified spectral library in combination with the PIONA+ software, accurate identification and quantification of the hydrocarbon composition of pyrolysis oils from C4 through C30+ was possible with a limit of detection of 0.1 wt.%. To the best of our knowledge, this article is the first example of accurate PIONA-type quantification of pyrolysis oils by GC-VUV.

Quantification of the composition of liquid hydrocarbon streams: Comparing the GC-VUV to DHA and GCxGC.

Hydrocarbons analysis is important in the oil and gas industry, as stream composition has a strong impact on plant operations. The composition of hydrocarbon streams vary across a plant, which makes the selection of analytical methods challenging. Traditional methods for the evaluation of liquid hydrocarbon streams include the Detailed Hydrocarbon Analysis (DHA); however, non-traditional methods, such as comprehensive gas chromatography (GCxGC), are also utilized in the chemical industry, including Dow. This work details a comparison of analytical techniques available for such analyses, specifically, DHA and GCxGC compared to the recently introduced GC-Vacuum Ultra Violet (GC-VUV) system. Numerous liquid hydrocarbon streams were blended together to generate a composite and extensive matrix in terms of composition. Paraffin, isoparaffin, olefin, naphthene, and aromatic (PIONA) results are presented for the three techniques. All of those methods obtained relative standard deviations lower than 1.3% for five injections a day for three days. Standard addition curves were utilized to accurately quantify specific compounds in a liquid hydrocarbon stream, and these results were compared to the GC-VUV PIONA+ and DHA quantification procedures.

A micro-jet array for economic intensification of gas transfer in bioreactors.

Bioreactors are of interest for gas-to-liquid conversion of stranded or waste industrial gases, such as CO, CH4 , or syngas. Process economics requires reduction of bioreactor cost and size while maintaining intense production via rapid delivery of gases to the liquid phase (i.e., high kL a). Here, we show a novel bioreactor design that outperforms all known technology in terms of gas transfer energy efficiency (kL a per power density) while operating at high kL a (i.e., near 0.8 s-1 ). The reactor design uses a micro-jet array to break feedstock gas into a downward microbubble flow. Hydrodynamic and surfactant measurements show the reactor's advanced performance arises from its bubble breakage mechanism, which limits fluid shear to a thin plane located at an optimal location for bubble breakage. Power dissipation and kL are shown to scale with micro-jet diameter rather than reactor diameter, and the micro-jet array achieves improved performance compared to classical impinging-jets, ejector, or U-loop reactors. The hydrodynamic mechanism by which the micro-jets break bubbles apart is shown to be shearing the bubbles into filaments then fragmentation by surface tension rather than "cutting in half" of bubbles. Guided by these hydrodynamic insights, strategies for industrial design are given. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2710, 2019.

Ultrasound-assisted oxidative desulfurization and denitrogenation of liquid hydrocarbon fuels: A critical review.

Nowadays, a continuously worldwide concern for development of process to produce ultra-low sulfur and nitrogen fuels have been emerged. Typical hydrodesulfurization and hydrodenitrogenation technology deals with important difficulties such as high pressure and temperature operating condition, failure to treat some recalcitrant compounds and limitations to meet the stringent environmental regulations. In contrary an advanced oxidation process that is ultrasound assisted oxidative desulfurization and denitrogenation satisfies latest environmental regulations in much milder conditions with more efficiency. The present work deals with a comprehensive review on findings and development in the ultrasound assisted oxidative desulfurization and denitrogenation (UAOD) during the last decades. The role of individual parameters namely temperature, residence time, ultrasound power and frequency, pH, initial concentration and types of sulfur and nitrogen compounds on the efficiency are described. What's more another treatment properties that is role of phase transfer agent (PTA) and solvents of extraction step, reaction kinetics, mechanism of the ultrasound, fuel properties and recovery in UAOD are reviewed. Finally, the required future works to mature this technology are suggested.

Temperature Dependence of Optical Constants for Chinese Liquid Hydrocarbon Fuels in the Near-Infrared (NIR) Region from Room Temperature to 400 K.

An improved double-thickness method combined with genetic algorithm was developed to determine the optical constants of liquid hydrocarbon fuels. Different from traditional transmission measurement, it obtained the total transmittance of a window-liquid-window three-layer structure, which is the ratio of the transmission intensity of the filled cell and that of the empty sample compartment. Also, the change of the surface reflectance at the interface of the liquid sample and the optical window and the difference between forward reflection and back reflection are considered. Experiments were operated to measure spectra in the wavelength range of 0.83-2.2 µm using a Fourier transform infrared (FT-IR) spectrometer. To verify the reliability of this method, optical constants of the distilled water were determined from its experimental transmittance spectra and the results agreed well with published data. On the basis of verification, the transmittance spectra of Chinese No. -35 diesel fuel were measured at 300 K, 350 K, and 400 K with liquid sample thicknesses of 0.5 mm and 1.0 mm. Then the optical constants of the diesel sample were obtained and the temperature dependence was analyzed. Analytical results indicate that the biggest change of the extinction coefficient between 300 K and 400 K can reach 30%, while that of the refractive index is 4.7%.

Hydrodeoxygenation processes: advances on catalytic transformations of biomass-derived platform chemicals into hydrocarbon fuels.

Lignocellulosic biomass provides an attractive source of renewable carbon that can be sustainably converted into chemicals and fuels. Hydrodeoxygenation (HDO) processes have recently received considerable attention to upgrade biomass-derived feedstocks into liquid transportation fuels. The selection and design of HDO catalysts plays an important role to determine the success of the process. This review has been aimed to emphasize recent developments on HDO catalysts in effective transformations of biomass-derived platform molecules into hydrocarbon fuels with reduced oxygen content and improved H/C ratios. Liquid hydrocarbon fuels can be obtained by combining oxygen removal processes (e.g. dehydration, hydrogenation, hydrogenolysis, decarbonylation etc.) as well as by increasing the molecular weight via C-C coupling reactions (e.g. aldol condensation, ketonization, oligomerization, hydroxyalkylation etc.). Fundamentals and mechanistic aspects of the use of HDO catalysts in deoxygenation reactions will also be discussed.