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Ash deposited in the DPF cannot be burnt, which will affect the service life of DPF. However, previous works focused on the effect of ash on the engine exhaust emissions are limited. Therefore, the influence of ash on the emissions was studied in this work. The particle emissions, the gaseous emissions, and the unregulated emissions (carbonyl compounds and volatile organic compounds) were measured by an AMA4000 gaseous analyzer, ELPI, HPLC, and GC-MS, respectively. Research results indicate that the filtration efficiency decreases by 0.57-4.49% for accumulation mode particle of particulate matter, while it has very little effects on the other type and the particle number in the presence of ash. For regular gaseous pollutions, ash has no influence on CO2 and NOx emission, while CO and THC increase by 68.2% and 91.0%, respectively. For unregulated emissions, overall, carbonyl compounds increase by 41-150% and the BTEX decreases by 8.6-23.6% after ash formed. The change is mainly caused by the increase in the exhaust backpressure that plays a key role.

High altitude shows a great influence on vehicle emissions because of lower pressure and shortage of oxygen concentrations. In addition, type approval test of light duty vehicle is usually carried out below the elevation of 1000 m. In order to address the effect of high altitude on vehicle emissions, real driving emission (RDE) test procedure has been introduced in China VI emission regulation. Thus, the effects of altitude on the emissions from a China IV certificated light-duty diesel vehicle under real road driving conditions were investigated in this work. Research results show that CO emissions increased with the elevated altitude. At the altitude of 2990 m, the CO emissions increased by 209% in comparison with that of near sea level in whole test cycle. At specific test modes, CO emissions follow the sequence of urban > rural > motorway. Both PN and NOx emissions also rose with altitude while NOx emissions at 2990 m showed a decreasing tendency. In addition, different tendency between high altitudes and relative low altitudes was observed under specific test modes, which was probably related to the function of after-treatment device.

A series of model NOx storage-reduction (NSR) catalysts with different Rh/Pt weight ratios were prepared independently by wet impregnation and then mechanically mixed to investigate the effect of the Rh/Pt weight ratio on the overall NOx removal efficiency and nitrogen yield. XRD, EDS and H2-TPR studies indicated the coexistence of BaCO3, MnOx and BaMnO3 phases in the catalysts. Increasing Rh/Pt weight ratio enhanced NOx reduction under the rich phase, and improved overall N2-yield in the kinetic regime of NO conversion, but shows a negative effect in the equilibrium-limited regime above 400 °C.

The formation of ammonia (NH3) as a byproduct during the operation of a three-way catalyst (TWC) in a simulated exhaust stream was investigated using a commercially available Pd/Rh TWC under steady-state and lean/rich cycling conditions. Ion molecular reaction-mass spectrometry was applied to determine NO, NO2, and NH3 concentrations at a time resolution of 0.6 s. Catalyst aging was shown to result in a significant increase in the amount of NH3 formed, which has received limited attention in the literature to date. The selectivity toward NH3 formation has been shown to increase with the decrease in the oxygen storage capacity (OSC) of a TWC induced by thermal aging. NH3 has been shown to mainly form within the exhaust temperature range of 250-550 °C. Typical lambda and rich operational condition duration periods found in vehicle test procedures were also employed to investigate their effects on NH3 formation. The results suggest that a decrease in the lambda and/or an increase in the duration of rich operating conditions will lead to an increase in the selectivity toward NH3 formation. Improving the OSC of TWCs and effectively controlling the lambda near to 1.0 with limited duration in rich operating conditions are therefore significant factors in the reduction of NH3 emissions.

By selecting varieties of factors, designing experiment in groups and other methods, the cleaning and detoxification of chromium in construction† waste has been studied. Experimental results show that: When particle diameter is larger than 1cm, chromium and content are volatile in waste. On the opposite, the effect of particle size on the detoxification of waste is not significantly when it is smaller than 1cm. In addition, the type and concentration of detergent have a great influence on cleaning and detoxifying. Detoxification effects on chromium of citric acid (0.1mol/L, 0.5mol/L) and concentration hydrochloric acid (0.5mol/L, 1mol/L) are very efficient, and removal rate is up to 90%. Citric acid, oxalic acid, concentrated hydrochloric acid, and concentrated acetic acid have the best effect on Cr6+ removal works. Removal rate is more than 99%.

With the increase in worldwide automobile usage and the tightening of associated emissions legislation, the total demand of PGMs for use in automotive emission control catalysts is growing. Reducing the amount of required PGM in automotive catalysts as well as maintaining or improving the associated catalytic performance is an area of significant focus. This work presents a comparative study of the catalytic activity of Pd-only, Pd/Rh and Rh-only catalyst systems with respect to CO, HC and NOx conversion. The Rh-only catalyst has been shown to have the potential to improve CO and NOx conversions when functioning as a downstream catalyst compared with a Pd/Rh catalyst as well as reducing the usage of precious metals. In addition the formation of the three way catalysis by-products N2O and NH3 in different catalyst systems was investigated. The temperature of N2O and NH3 formation was shown to correlate with NOx light off temperatures and to vary depending upon the catalyst system employed and ageing conditions. The Rh-only catalyst was shown to generate the highest amount of N2O and the Pd-only catalyst the highest amount of NH3.