Effects of Selective Catalytic Reduction on the Emissions of Persistent Organic Pollutants from a Heavy-Duty Diesel Engine

Abstract

The emissions of persistent organic pollutants (POPs) from diesel engines is becoming more important due to their proximity to human beings compared to stationary sources whose emission have been well controlled over the years. The selective catalytic reduction (SCR) have been adopted in the heavy-duty diesel engine (HDDE) to reduce the nitrogen oxide (NO x ). SCR has also been reported to reduce the polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polychlorinated biphenyls (PCBs). However, the memory effect and reformation of persistent organic pollutants (POPs) during SCR operation are not well understood. This study investigated the effect of Copper-zeolite SCR (CuZ SCR) on PCDD/F, PCB, polybrominated dibenzo-p-dioxin and dibenzofuran (PBDD/F), and polybrominated biphenyl (PBB) emissions from a HDDE at 50% and 75% engine load. Notably, PCDD/F and PCB toxicity emissions increased by 78.4% and 201%, respectively. The dominant PCDD/F congeners were OCDD, OCDF, 1,2,3,4,6,7,8-HpCDD, and 1,2,3,4,6,7,8-HpCDF and PCB-105, PCB-118 and PCB-77 for PCBs. More PCDFs were formed compared to PCDDs and lower chlorinated congeners increased more than the higher chlorinated ones. There was also an increase of PBDD/F concentrations from undetectable levels (ND) to 0.247 pg TEQ Nm -3 (4.00 pg TEQ L -1 ) after the SCR. However, only 1,2,3,4,6,7,8-HpBDF and OBDF contributed to the concentrations. PBBs was the only compound measured that reduced after the SCR. The only congener detected before and after the SCR was PBB 15. Consequently, the CuZ SCR could be a source of POPs under mid and high engine loads in this study. Further detail research is required to focus on the formation of POPs on the catalyst surfaces and structures.

Passive Air Sampling of PCDD/Fs, PCBs, PAEs, DEHA, and PAHs from Informal Electronic Waste Recycling and Allied Sectors in Indian Megacities

“…PCB-169 levels correlated with vehicular average numbers ( R 2 = 0.85, p < 0.05) recorded in these Indian cities. The catalytic reduction process in internal combustion engines especially diesel engines are major sources of these congeners . It is important to note that PCB-169 showed a strong correlation with PCB-126 at RS sites ( R 2 = 0.95, p < 0.05) thereby indicating combustion sources from nearby hotspots.…”

“…The catalytic reduction process in internal combustion engines especially diesel engines are major sources of these congeners. 85 It is important to note that PCB-169 showed a strong correlation with PCB-126 at RS sites (R 2 = 0.95, p < 0.05) thereby indicating combustion sources from nearby hotspots. Significant correlation was observed between DEHP with Pyr (R 2 = 0.85, p < 0.…”

The Characterization and SCR Performance of Mn-Containing α-Fe2O3 Derived from the Decomposition of Siderite

“…Nitrogen oxides (NO x ) emitted from various sources are a major atmospheric pollutant, causing acid rain, photochemical smog, and endangering human health and the ecological environment [1][2][3][4]. The world energy infrastructure being based on fossil energy further aggravates NO x pollution to a certain extent.…”

Polycyclic Aromatic Hydrocarbons (PAHs) and nitrated analogs associated to particulate matter emission from a Euro V-SCR engine fuelled with diesel/biodiesel blends

“…The injection of urea and a catalyst ensures reductions of up to 90% in NO x emissions, through a reduction reaction of NO x and NH 3 resulting in nitrogen and water (Amanatidis et al, 2014;Bacher et al, 2015). Nevertheless, SCR technology is not without its challenges, such as the emission of NH 3 , stoichiometric disproportion of urea consumption, cost, and deactivation of the catalyst by deposition (Cheruiyot et al, 2017). The best reported SCR efficiency is achieved at high engine loads and temperatures (approximately 400°C) (Cheruiyot et al, 2017).…”

“…Nevertheless, SCR technology is not without its challenges, such as the emission of NH 3 , stoichiometric disproportion of urea consumption, cost, and deactivation of the catalyst by deposition (Cheruiyot et al, 2017). The best reported SCR efficiency is achieved at high engine loads and temperatures (approximately 400°C) (Cheruiyot et al, 2017). However, the added urea increases the probability of unintended formation of Nitro-PAHs through PAHs nitration (Liu et al, 2015).…”