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The development of simple and cost-effective analytical methods is indispensable for law enforcement officials in the rapid screening for large quantities of seized drugs. Handheld infrared spectroscopy has been used with Bayes discrimination analysis (BDA), k nearest neighbor (KNN), support vector machine (SVM), decision-making tree (DT), and random forest (RF) chemometrics to characterize 3,4-methylenedioxy-N-methylamphetamine (MDMA), ketamine, and benzodiazepine samples. Spectral data were pretreated by normalization, multivariate scatter correction, Savitzky-Golay smoothing algorithm, and automatic baseline correction. Principal component analysis (PCA) was employed to reduce the dimensionality of spectral data, while BDA, KNN, SVM, DT, and RF, as supervised pattern recognition methods, were implemented and their parameters were optimized to identify the samples. The results showed that SVM was optimal among the models, followed by DT, KNN, BDA, and RF. The optimal model, based upon polynomial kernel function, achieved an accuracy of 100% (training set) and 100% (test set) for all samples and was used to further distinguish the additives in MDMA, ketamine, and benzodiazepine samples. In the MDMA samples, 42 samples contained caffeine, 23 contained glucose, and 21 contained starch. In the ketamine samples, 34 contained caffeine, 13 contained glucose, and 12 contained phenacetin. In the benzodiazepine samples, estazolam, diazepam, lorazepam, clonazepam, and nitrazepam were identified. 5 samples were misidentified into other categories. This study demonstrated that handheld infrared spectroscopy with chemometrics is a reliable and desirable approach for the rapid and nondestructive identification of MDMA, ketamine, and benzodiazepine with high potential in practical applications. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic steam gasification of waste polyethylene (PE) from municipal solid waste (MSW) to produce syngas (H2 +CO) with NiO/γ-Al2O3 as catalyst in a bench-scale downstream fixed bed reactor was investigated. The influence of the reactor temperature on the gas yield, gas composition, steam decomposition, low heating value (LHV), cold gas efficiency and carbon conversion efficiency was investigated at the temperature range of 700–900°C, with a steam to waste polyethylene ratio of 1.33. Over the ranges of experimental conditions examined, NiO/γ-Al2O3 catalyst revealed better catalytic performance as a view of increasing product gas yield and of decreasing char and liquid yields in the presence of steam. Higher temperature resulted in more H2 and CO production, higher carbon conversion efficiency and product gas yield. The highest syngas (H2 +CO) content of 64.35mol%, the highest H2 content of 36.98mol%, and the highest CO content of 27.37mol%, were achieved at the highest temperature level of 900°C. Syngas produced with a H2/CO molar ratio in the range of 0.83–1.35, was highly desirable as feedstock for Fischer–Tropsch synthesis for the production of transportation fuels. [Copyright &y& Elsevier]

Abstract: In the present study the catalytic steam gasification of MSW to produce hydrogen-rich gas or syngas (H2 +CO) with calcined dolomite as a catalyst in a bench-scale downstream fixed bed reactor was investigated. The influence of the catalyst and reactor temperature on yield and product composition was studied at the temperature range of 750–950°C, with a steam to MSW ratio of 0.77, for weight hourly space velocity of 1.29h−1. Over the ranges of experimental conditions examined, calcined dolomite revealed better catalytic performance, at the presence of steam, tar was completely decomposed as temperature increases from 850 to 950°C. Higher temperature resulted in more H2 and CO production, higher carbon conversion efficiency and dry gas yield. The highest H2 content of 53.29mol%, and the highest H2 yield of 38.60mol H2/kg MSW were observed at the highest temperature level of 950°C, while, the maximum H2 yield potential reached 70.14mol H2/kg dry MSW at 900°C. Syngas produced by catalytic steam gasification of MSW varied in the range of 36.35–70.21mol%. The char had a highest ash content of 84.01% at 950°C, and negligible hydrogen, nitrogen and sulphur contents. [Copyright &y& Elsevier]

Abstract: Biomass micron fuel (BMF) produced from feedstock (energy crops, agricultural wastes, forestry residues and so on) through an efficient crushing process is a kind of powdery biomass fuel with particle size of less than 250μm. Based on the properties of BMF, a cyclone gasifier concept has been considered in our laboratory for biomass gasification. The concept combines and integrates partial oxidation, fast pyrolysis, gasification, and tar cracking, as well as a shift reaction, with the purpose of producing a high quality of gas. In this paper, characteristics of BMF air gasification were studied in the gasifier. Without outer heat energy input, the whole process is supplied with energy produced by partial combustion of BMF in the gasifier using a hypostoichiometric amount of air. The effects of equivalence ratio (ER) and biomass particle size on gasification temperature, gas composition, gas yield, low-heating value (LHV), carbon conversion and gasification efficiency were studied. The results showed that higher ER led to higher gasification temperature and contributed to high H2-content, but too high ER lowered fuel gas content and degraded fuel gas quality. A smaller particle was more favorable for higher gas yield, LHV, carbon conversion and gasification efficiency. And the BMF air gasification in the cyclone gasifier with the energy self-sufficiency is reliable. [Copyright &y& Elsevier]

Abstract: The catalytic steam gasification of biomass was carried out in a lab-scale fixed bed reactor in order to evaluate the effects of particle size at different bed temperatures on the gasification performance. The bed temperature was varied from 600 to 900°C and the biomass was separated into five different size fractions (below 0.075mm, 0.075–0.15mm, 0.15–0.3mm, 0.3–0.6mm and 0.6–1.2mm). The results show that with decreasing particle size, the dry gas yield, carbon conversion efficiency and H2 yield increased, and the content of char and tar decreased. And the differences due to particle sizes in gasification performance practically disappear as the higher temperature bound is approached. Hydrogen and carbon monoxide contents in the produced gas increase with decreasing particle size at 900°C, reaching to 51.2% and 22.4%, respectively. [Copyright &y& Elsevier]