Production and characterization of bio-oil from algae using pyrolysis

Pyrolysis of the algae (chlorophyceac) was carried out using fixed bed reactor at 4500C. The mass balance of the pyrolysed algae were liquid fraction (oil) (10%), gaseous product (11%), solid product (char) (79%) and extent of conversion (21%. The proximate analysis of powdered sample was carried out in accordance with the official method of analytical chemistry (AOAC). The moisture content, ash content, volatile matter and fixed carbon determined were 3 + 0.33, 70.3 + 0.5, 6.3 + 0.3 and 20.2 + 0.07 respectively. The result obtained indicate that algae (chlorophyceae) could be used as feedstock for generation of pyrolysed oil which could probably be upgraded to fuel for both domestic and industrial purposes.

Chemical Decomposition of the TFSI Anion Under Aqueous Basic Conditions

Understanding the interfacial reactivity of aqueous electrolytes is crucial for their use in future batteries. We investigate the reactivity of the bis(trifluoromethane)sulfonimide (TFSI) anion when exposed to a strong alkaline medium, by means of ab initio molecular dynamics and enhanced sampling techniques. In particular, we study the nucleophilic attack by the hydroxide anion, which was proposed as a mechanism for the formation of the solid electrolyte interphase at the negative electrode with water-in-salt electrolytes. While in the gas phase we recover a stable gaseous product, namely fluoroform, we observe the formation of trifluoromethanol in strong basic conditions, which then rapidly deprotonates to form CF3O-. This anion was suggested recently as a key compound leading to the formation of a solid electrolyte interphase on an Si-C anode. Such an approach could be leveraged to discover convenient additives leading to the formation of a stable interphase.

Syngas Underground Coal Gasification (UCG) Testing of Fracture Type Subbituminous Coal in Laboratory Scale

Underground Coal Gasification is a method used to convert underground coal seams into a gaseous product commonly called synthetic gas through a flammable chemical process without going through a conventional mining process. The UCG concept was first developed in England which was then continued by the Soviet Union in field trials of UCG which was used as a power plant. In Indonesia, Tekmira has begun to research UCG, but there are very few publications on UCG. Therefore, it is necessary to conduct research on laboratory scale UCG for analysis of gas products to support the study of renewable energy. UCG testing begins with sample preparation followed by laboratory-scale coal gasification testing. There is a sample of coal used in the test, namely Subbituminous Coal from Tanjung Enim, South Sumatra. Initial combustion is carried out by flowing propane gas into the reactor tube using a burner. Furthermore, a mixture of oxygen gas and compressed air is used to keep the coals burning. After obtaining the gas from the combustion, then gas sampling is carried out using a suction pump which will be stored in a tedlar gas bag. Combustion gas products will be checked for syngas concentration using a Gas Chromatography tool to determine the concentration of CH4, CO2 and O2 gases. From the tests that have been carried out, the gas concentrations of O2 are 3.67%, CO2 41.51%, and CH4 6.93%. Coal in the confined test conditions has good conditions with indications of seeing the concentration of CH4, O2, and CO2 gas.

Prediction of Probabilistic Shock Initiation Thresholds of Energetic Materials through Evolution of Thermal-mechanical Dissipation and Reactive Heating

The ignition threshold of an energetic material (EM) quantifies the macroscopic conditions for the onset of self-sustaining chemical reactions. The threshold is an important theoretical and practical measure of material attributes that relate to safety and reliability. Historically, the thresholds are measured experimentally. Here, we present a new Lagrangian computational framework for establishing the probabilistic ignition thresholds of heterogeneous EM out of the evolutions of coupled mechanical-thermal-chemical processes using mesoscale simulations. The simulations explicitly account for microstructural heterogeneities, constituent properties, and interfacial processes and capture processes responsible for the development of material damage and the formation of hotspots in which chemical reactions initiate. The specific mechanisms tracked include viscoelasticity, viscoplasticity, fracture, post-fracture contact, frictional heating, heat conduction, reactive chemical heating, gaseous product generation, and convective heat transfer. To determine the ignition threshold, the minimum macroscopic loading required to achieve self-sustaining chemical reactions with rate of reactive heat generation exceeding the rate of heat loss due to conduction and other dissipative mechanisms is determined. Probabilistic quantification of the processes and the thresholds are obtained via the use of statistically equivalent microstructure samples sets (SEMSS). The predictions are in agreement with available experimental data.

Direct electrosynthesis of 52% concentrated CO on silver’s twin boundary

The gaseous product concentration in direct electrochemical CO2 reduction is usually hurdled by the electrode’s Faradaic efficiency, current density, and inevitable mixing with the unreacted CO2. A concentrated gaseous product with high purity will greatly lower the barrier for large-scale CO2 fixation and follow-up industrial usage. Here, we developed a pneumatic trough setup to collect the CO2 reduction product from a precisely engineered nanotwinned electrocatalyst, without using ion-exchange membrane. The silver catalyst’s twin boundary density can be tuned from 0.3 to 1.5 × 104 cm−1. With the lengthy and winding twin boundaries, this catalyst exhibits a Faradaic efficiency up to 92% at −1.0 V and a turnover frequency of 127 s−1 in converting CO2 to CO. Through a tandem electrochemical-CVD system, we successfully produced CO with a volume percentage of up to 52%, and further transformed it into single layer graphene film.

Modelling, computation and analysis on combustion of explosives

When an explosive burns, gaseous products are formed as a result. The interaction of the burning solid and gas is not well understood. More specifically, the process of the gaseous product heating the explosive is yet to be explored in detail. The present work sets out to fill some of that gap using mathematical modelling: this aims to track the temperature profile in the explosive. The work begins by modelling single-step reactions using a simple Arrhenius model. The model is then extended to include three-step reaction. An alternative asymptotic approach is also employed. There is close agreement between results from the full reaction-diffusion problem and the asymptotic problem.

Py–FTIR–GC/MS Analysis of Volatile Products of Automobile Shredder Residue Pyrolysis

Automobile shredder residue (ASR) pyrolysis produces solid, liquid, and gaseous products, particularly pyrolysis oil and gas, which could be used as renewable alternative energy resources. Due to the primary pyrolysis reaction not being complete, the yield of gaseous product is low. The pyrolysis tar comprises chemically unstable volatiles before condensing into liquid. Understanding the characteristics of volatile products will aid the design and improvement of subsequent processes. In order to accurately analyze the chemical characteristics and yields of volatile products of ASR primary pyrolysis, TG–FTIR–GC/MS analysis technology was used. According to the analysis results of the Gram–Schmidt profiles, the 3D stack plots, and GC/MS chromatograms of MixASR, ASR, and its main components, the major pyrolytic products of ASR included alkanes, olefins, and alcohols, and both had dense and indistinguishable weak peaks in the wavenumber range of 1900–1400 cm−1. Many of these products have unstable or weaker chemical bonds, such as =CH–, =CH2, –C=C–, and –C=CH2. Hence, more syngas with higher heating values can be obtained with further catalytic pyrolysis gasification, steam gasification, or higher temperature pyrolysis.

Photosynthetic Co-production of Succinate and Ethylene in a Fast-Growing Cyanobacterium, Synechococcus elongatus PCC 11801

Cyanobacteria are emerging as hosts for photoautotrophic production of chemicals. Recent studies have attempted to stretch the limits of photosynthetic production, typically focusing on one product at a time, possibly to minimise the additional burden of product separation. Here, we explore the simultaneous production of two products that can be easily separated: ethylene, a gaseous product, and succinate, an organic acid that accumulates in the culture medium. This was achieved by expressing a single copy of the ethylene forming enzyme (efe) under the control of PcpcB, the inducer-free super-strong promoter of phycocyanin β subunit. We chose the recently reported, fast-growing and robust cyanobacterium, Synechococcus elongatus PCC 11801, as the host strain. A stable recombinant strain was constructed using CRISPR-Cpf1 in a first report of markerless genome editing of this cyanobacterium. Under photoautotrophic conditions, the recombinant strain shows specific productivities of 338.26 and 1044.18 μmole/g dry cell weight/h for ethylene and succinate, respectively. These results compare favourably with the reported productivities for individual products in cyanobacteria that are highly engineered. Metabolome profiling and 13C labelling studies indicate carbon flux redistribution and suggest avenues for further improvement. Our results show that S. elongatus PCC 11801 is a promising candidate for metabolic engineering.

Pyrolysis of Waste Palm Oil in the Presence of Steam

This work ranges among studies dedicated to valorization of waste vegetable oils. In the present study, the pyrolysis of the waste palm oil was performed in presence of steam, in a tubular pyrolysis reactor operated in a continuous mode. The raw used in the pyrolysis reaction is the frying waste palm oil and the reactor was operated at high temperature (575 -625°C) and reaction time of 72s and 144s, at a steam: oil ratio of 0.1 -0.2. Valuable compounds such as olefins (ethylene, propylene) were obtained in the process, and they can be used further as raw materials in the chemical and petrochemical industry. The gaseous product resulted contained high ethylene and propylene concentrations: 18.89 - 25.5% and 13.33-15.05%, respectively. Based on the experimental results, some linear equations were developed to predict the products yields, and the coefficients of the model were statistically verified. These equations can serve at scaling up the pyrolysis process. Keywords: Steam cracking, vegetable oil pyrolysis, yield prediction, mathematical model