Modeling NOx Storage and Reduction for a Diesel Automotive Catalyst Based on Synthetic Gas Bench Experiments

Abstract

To comply with stringent NO x emission regulations, automotive diesel engines require advanced aftertreatment catalytic systems, such as lean NO x traps (LNTs). Considering that test bench and chassis dyno experimental campaigns are costly and require a vast use of resources for the generation of data; therefore, reliable and computationally efficient simulation models are essential in order to identify the most promising technology mix to satisfy emission regulations. In the literature, a large number of simulation models for LNT kinetics can be found, realized for laboratory-scale samples and validated over synthetic gas bench (SGB) experimental tests, while full-size models validated over engine-dyno driving cycle data, crucial for industrial applications, are missing. In the current work, a simulation model of an LNT device is built to predict NO x storage and reduction, starting from SGB laboratory tests and finally validated over driving cycle data. The experiments including light-off, NO x storage and reduction (NSR), and oxygen storage capacity (OSC) characterization, were performed on a laboratory-scale sample extracted from a full-scale monolith. Light-off tests have been conducted under a temperature ramp cycle from 120 °C to 380 °C, while OSC and NSR tests were performed under isothermal conditions at five temperature levels, ranging from 150 °C to 400 °C. OSC tests were performed to characterize oxygen storage capacity of ceria sites and water gas shift (WGS) reaction over the precious metals by controlling inlet species concentrations with periodic lean/rich pulses. NSR experiments were then performed by alternating a lean inlet composition to reproduce adsorption/desorption of NO x with a rich inlet composition feed with three reductants (H 2 , CO, and C 3 H 6 ) to replicate NO x reduction reactions. A global kinetic scheme was defined by means of a one-dimensional (1D) engine simulation fluid-dynamic code, GT-SUITE, to model oxidation reactions (CO, HC, NO), NO x adsorption/desorption, oxygen storage and NO x reduction reactions. The kinetic parameters were obtained using Arrhenius plots with the aim to minimize the error between simulated and experimental NO x , reductants, N 2 O and NH 3 concentrations, reaching a satisfactory agreement with measurements.

Mesoporous Co3O4 Nanoparticles with Enriched Oxygen Defects for Efficient NO Oxidation

“…Furthermore, with the increase of GHSV from 180,000 to 30,000 h –1 , a marginal decrease in the NO conversion efficiency is observed for all samples, which is attributed to a lower contact time between the reactants and catalysts. As outlined in Figure S2 and Table S2, the T 50 (the half conversion temperature) was only 221 °C for M-Co 3 O 4 , outperforming the F-Co 3 O 4 ( T 50.0 = 240 °C) and B-Co 3 O 4 ( T 66.0 = 292 °C), YMn 2 O 5 ( T 50.0 = 285 °C), La 1– x Sr x CoO 3 ( T 50.0 = 250 °C), etc. These findings unequivocally showcase the exceptional catalytic activity of M-Co 3 O 4 in NO oxidation, solidifying its potential as an effective catalyst in pollution remediation applications.…”

“…As it is widely recognized, platinum group metals (PGMs), such as Pt, PdO, Ru, and PtPd alloy, have been the subject of extensive research when it comes to NO oxidation. Despite their promising catalytic activity, the high cost and limited availability of PGMs have hindered their widespread use in practical applications .…”

Making precious metals cheap: A sonoelectrochemical – Hydrodynamic cavitation method to recycle platinum group metals from spent automotive catalysts

“…PGMs inertness require large amounts of strong acids and powerful oxidants which creates a large environmental footprint. The large amounts of chemicals and energy used in PGM recycling acted as the catalyst in developing alternative recycling routes, such as: two-step microwave-assisted leaching [4] , [5] ; biohydrometallurgical processes [6] , [7] ; pyrometallurgy [8] , [9] , [10] . The above-mentioned technologies used for PGM extraction are economically viable only in large recycling facilities.…”

Optimizing Washcoating Conditions for the Preparation of Zeolite-Based Cordierite Monoliths for NOx CH4-SCR: A Required Step for Real Application

“…Though the development of new catalytic formulations performed at lab-scale is commonly made considering powder formulations, commercial applications of catalysts for real emission control systems (both for automotive and stationary sources) consider the use of honeycomb monoliths. − In particular, for automotive applications, ceramic monoliths made of cordierite (2MgO·2Al 2 O 3 ·5SiO 2 ) are one of the most considered structures for the majority the after-treatment systems, namely, lean NO x traps (LNT), − 3-ways catalysts, , diesel oxidation catalysts (DOC), − and selective catalytic reduction by ammonia (NH 3 -SCR). , This material is often considered due to its mechanical strength and its low thermal expansion coefficient. Additionally, its porosity and pore size distribution is suitable to be used for washcoat application due to its favorable adherence properties. , …”