Simultaneous abatement of diesel soot and NOX emissions by effective catalysts at low temperature: An overview

The diesel engine generally achieves the highest fuel, energy, and thermal efficiency due to its very high compression/expansion ratio (14:1 to 25:1). Diesel engines can have a thermal efficiency that exceeds 50%. The main problem is that they emit more pollution like fine black soot particulates (C₈H to C₁₀H) and nitrogen oxides (NO_X). These pollutants have been causing serious problems for human health and the global environment and also impacts on the engine. There are many types of catalysts investigated for simultaneous control of these two pollutants, i.e., platinum group metals (PGM; Pt, Pd, Rh, and Ir) based, spinel-type oxides, hydrotalcite, rare earth metal oxides, mixed transient metal oxides, etc. The high raw material cost of PGM catalysts has become a significant issue, so developing non-PGM catalysts are one of the promising challenges. There are no extra reductants required because soot catalytically oxidizes itself in the presence of NO_X at a faster rate than molecular oxygen and simultaneously NO_X is reduced to nitrogen. The order of oxidation potential of NO_X to oxidized soot in comparison to molecular oxygen is as follows: NO₂ > NO > O₂. To meet the very strict EPA US 2010 and Euro VI regulations of particulate matter (PM) and NO_X for heavy-duty and light-duty vehicular stringent emission, it is very important to apply the integrated catalytic systems to significantly remove PM and NO_X simultaneously. Many papers related to simultaneous control of soot and NO_X over different catalysts have been published but till now some of effective catalysts showing high conversion at low temperatures (possibly within the range typical of diesel exhaust: 150–450°C) have not been reviewed. Thus, this article provides a summary of published information regarding the effective catalysts, their preparation methods, properties, and application for simultaneous control of diesel soot and NO_X.     

Cytotoxic Activity and Structure–Activity Relationship of Triazole‐Containing Bis(Aryl Ether) Macrocycles

Cancer continues to be a worldwide health problem. Certain macrocyclic molecules have become attractive therapeutic alternatives for this disease because of their efficacy and, frequently, their novel mechanisms of action. Herein, we report the synthesis of a series of 20‐, 21‐, and 22‐membered macrocycles containing triazole and bis(aryl ether) moieties. The compounds were prepared by a multicomponent approach from readily available commercial substrates. Notably, some of the compounds displayed interesting cytotoxicity against cancer (PC‐3) and breast (MCF‐7) cell lines, especially those bearing an aliphatic or a trifluoromethyl substituent on the N‐phenyl moiety (IC₅₀<13 μm ). Additionally, some of the compounds were able to induce apoptosis relative to the solvent control; in particular, (Z)‐N‐cyclohexyl‐7‐oxo‐6‐[4‐(trifluoromethyl)phenyl]‐1¹H‐3,10‐dioxa‐6‐aza‐1(4,1)‐triazola‐4(1,3),9(1,4)‐dibenzenacyclotridecaphane‐5‐carboxamide ( 12 f ) was the most potent in this regard (22.7 % of apoptosis).     

Effect of bacterial inoculum ratio in mixed culture for decolourization and detoxification of pulp paper mill effluent

BACKGROUND: Effluent released from industry is a mixture of various pollutants. For the degradation of complex pollutants, mixed bacterial cultures can be more effective than a single culture. This study investigated the balance of bacterial populations in a mixed culture for maximum reduction of pollutants. RESULTS: This study deals with the degradation and detoxification of pulp paper mill effluent (PPME) by three bacterial strains, i.e. Serratia marcescens, Serratia liquefaciens and Bacillus cereus in different ratios, and found that two ratios, 4:1:1 and 1:4:1, were effective for the degradation of PPME. These ratios reduced the various pollution parameters. Enzyme bioassay revealed that more enzyme was produced during degradation for the ratio 4:1:1. High performance liquid chromatography (HPLC) analysis showed that the ratio 4:1:1 degraded 95% of lignin and related compounds, and chlorophenols up to 98%, whereas ratio 1:4:1 reduced lignin by 84% and chlorophenols by 58% after 7 days incubation. Degradation products were confirmed by gas chromatography–mass spectrometry (GC‐MS) analysis. A seed germination bioassay on Phaseolous mungo L. revealed that toxicity was reduced by the ratio 4:1:1. CONCLUSION: Due to variable potential of different bacteria show variation in their growth pattern at any contaminated site. This study shows that an appropriate ratio of mixed cultures is required for maximum degradation and detoxification of PPME. Copyright © 2012 Society of Chemical Industry     

Second row transition metal sulfides for the hydrotreatment of coal-derived naphtha I. Catalyst preparation, characterization and comparison of rate of simultaneous removal of total sulfur, nitrogen and oxygen

Naphtha derived from an Illinois No. 6 coal contains appreciable quantities of sulfur-, nitrogen- and oxygen-containing compounds. The hydrotreatment of this naphtha has been evaluated over unsupported transition metal sulfide catalysts of the second row in the Periodic Table. The catalysts were prepared by a room temperature precipitation reaction. Surface areas, crystalline phase and particle size distributions were determined by Brunauer-Emmet-Teller (BET), X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. A comparison of average particle sizes calculated from these three techniques has enabled the understanding of the morphology of the transition metal sulfides. The catalysts exhibit a so-called volcano plot for the HDS of dibenzothiophene. Similar so-called volcano plots are also exhibited for the simultaneous hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and the hydrodeoxygenation (HDO) of the coal-derived naphtha containing a mixture of heteroatoms. The order of reactivity of the transition metal catalysts is the same for all three of the processes. Ruthenium sulfide (RuS₂) is the most active catalyst for HDS, HDN and HDO of the coal-derived naphtha.     

Synthesis and spectral,thermal, and photocrosslinking studies of poly(benzylidene phosphoramide ester)s

A new class of poly(benzylidene phosphoramide ester)s containing a photoreactive benzylidene chromophore in the main chain were synthesized from bis(4-hydroxy-3-methoxy benzylidene) acetone with various substituted N-aryl phosphoramidic dichlorides by an interfacial polycondensation technique. The synthesized polymers were characterized by inherent viscosity, IR, and ¹H-, ¹³C-, and ³¹P-NMR spectroscopy. The molecular weights of these polymers were determined by gel permeation chromatography. These polymers were studied for their thermal stability and photochemical properties. Thermal properties were evaluated by thermogravimetric analysis and differential scanning calorimetry. It was found that halogen-containing polymers show a higher thermal stability than that of nonhalogenated polymers. The photocrosslinking property of these polymers was studied by ultraviolet spectroscopy. The photoreactive benzylidene chromophore in the main chain dimerizes via 2π + 2π cycloaddition reaction to form a cyclobutane derivative and leads to crosslinking. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2151–2157, 1997     

Bifurcation analysis of index infinity DAE parabolic models describing reactors and reacting flows

We show that most steady‐state models of chemical reactors and reacting flows in which convection effects are dominant and diffusion/conduction is neglected in the flow direction but included in the transverse directions, may change from parabolic type with a unique solution to index infinity differential‐algebraic equation (DAE) type with an infinite number of steady‐state solutions depending on the values of the reaction parameters. When a model is of index infinity, standard numerical methods may find only one of the solutions corresponding to latest possible ignition. We present complete bifurcation analysis of these models, a method for finding all solutions, determine the stability and, for some simpler cases, the domain of initial conditions attracted to these states. We also demonstrate that the various steady‐state solutions of the DAE systems are best found by integrating the transient hyperbolic versions of the models with appropriately selected capacitance terms and initial conditions. © 2016 American Institute of Chemical Engineers AIChE J, 63: 295–305, 2017