scholarly journals Light-off Investigation of Oxymethylene Ether (OME) Considering the Presence of the Exhaust Components Heptane, Carbon, and Nitrogen Monoxide

2021 ◽  
Author(s):  
Florian Rümmele ◽  
Alexander Susdorf ◽  
Syed Muhammad Salman Haider ◽  
Robert Szolak
Keyword(s):  
Nitrogen Monoxide ◽  
High Reactivity ◽  
Oxidation Temperature ◽  
Oxidation Catalyst ◽  
Temperature Programmed Oxidation ◽  
Exhaust Temperature ◽  
Fuel Blends ◽  
Temperature Programmed ◽  
Management Approaches ◽  
Exhaust After Treatment

AbstractSynthetic fuels and fuel blends like OMEs can contribute to tank-to-wheel CO2 emission savings. At the same time, it is known that these fuels have a lower exhaust temperature compared to conventional diesel. This effect has major impact on the exhaust after-treatment system, particularly in cold start conditions. This paper investigates the light-off behavior of exhaust gases containing OMEs by temperature-programmed oxidation experiments using a state-of-the-art oxidation catalyst. The main side product of catalytic oxidation of OMEs between 100 °C and the oxidation temperature T50, which was around 160 °C, was shown to be formaldehyde. While alkane oxidation, in this case heptane, was little influenced by OME oxidation, the oxidation temperature T50 of CO increases by more than 10 °C by OME addition. Nitrogen monoxide impeded the oxidation of OME in a similar way to the other components investigated. Due to the amount of FA produced and its toxicity, it could be concluded that it is necessary to heat up exhaust after-treatment systems of OME diesel engines even faster than conventional diesel exhaust after-treatment systems. The relatively high reactivity of OME on oxidation catalyst can be used by active thermal management approaches.

scholarly journals Performance and Regeneration of Methane Oxidation Catalyst for LNG Ships

2021 ◽  
Vol 9 (2) ◽  
pp. 111
Author(s):  
Kati Lehtoranta ◽  
Päivi Koponen ◽  
Hannu Vesala ◽  
Kauko Kallinen ◽  
Teuvo Maunula
Keyword(s):  
Methane Oxidation ◽  
Sulfur Poisoning ◽  
Oxidation Catalyst ◽  
Lean Burn ◽  
Marine Fuel ◽  
Efficient Catalyst ◽  
Worst Case ◽  
Exhaust Temperature ◽  
Unintended Effect ◽  
Methane Slip

Liquefied natural gas (LNG) use as marine fuel is increasing. Switching diesel to LNG in ships significantly reduces air pollutants but the methane slip from gas engines can in the worst case outweigh the CO2 decrease with an unintended effect on climate. In this study, a methane oxidation catalyst (MOC) is investigated with engine experiments in lean-burn conditions. Since the highly efficient catalyst needed to oxidize methane is very sensitive to sulfur poisoning a regeneration using stoichiometric conditions was studied to reactivate the catalyst. In addition, the effect of a special sulfur trap to protect the MOC and ensure long-term performance for methane oxidation was studied. MOC was found to decrease the methane emission up to 70–80% at the exhaust temperature of 550 degrees. This efficiency decreased within time, but the regeneration done once a day was found to recover the efficiency. Moreover, the sulfur trap studied with MOC was shown to protect the MOC against sulfur poisoning to some extent. These results give indication of the possible use of MOC in LNG ships to control methane slip emissions.

N2O Temperature-Programmed Oxidation and EXAFS Studies on the Dispersion of Copper in Ceria-Supported Nanocatalysts

2005 ◽  
Vol 17 (15) ◽  
pp. 3935-3943 ◽  
Author(s):  
A. Tschöpe ◽  
J. Markmann ◽  
P. Zimmer ◽  
R. Birringer ◽  
Chadwick
Keyword(s):  
Temperature Programmed Oxidation ◽  
Temperature Programmed

Isothermal and temperature-programmed oxidation of CH over Pt{}-(1×2)

2002 ◽  
Vol 505 ◽  
pp. 58-70 ◽  
Author(s):  
D.T.P. Watson ◽  
J.J.W. Harris ◽  
D.A. King
Keyword(s):  
Temperature Programmed Oxidation ◽  
Temperature Programmed

scholarly journals EFFECT OF PREPARATION METHOD OF Ni CATALYST USING BENTONITE AS THE SUPPORT MATERIAL

2010 ◽  
Vol 3 (2) ◽  
pp. 118-125
Author(s):  
Hery Haerudin ◽  
Silvester Tursiloadi ◽  
Galuh Widiyarti ◽  
Wuryaningsih Sri Rahayu
Keyword(s):  
Nickel Catalyst ◽  
Preparation Method ◽  
Nickel Content ◽  
Peak Position ◽  
Single Peak ◽  
Main Peak ◽  
Ni Catalyst ◽  
Support Material ◽  
Temperature Programmed Oxidation ◽  
Temperature Programmed

Nickel catalyst has been prepared impregnation and precipitation with nickel content of 20% and 25% each using bentonite as support material. The effects of the preparation method were studied using temperature programmed oxidation (TPO) and temperature programmed reduction (TPR) and by determination of its specific surface area. The activity of catalysts has been tested in the hydrogenation of palm oil. The catalyst with 20% of nickel and prepared by impregnation shows a single peak at 301°C, compared to catalyst with 25% of nickel prepared by the same method which has a peak at 304°C and a shoulder at 330°C. The reduction curves of both catalysts, those are prepared by impregnation, show a homogeneity indicated by a high main peak at 426°C (20% Ni) and 430°C (25% Ni). The 25% nickel catalyst by impregnation has a shoulder at 508°C. The catalysts prepared by precipitation show peaks at 508°C and 661°C for 20% of Ni and peaks at 419°C and 511°C for 25% of Ni. The reduction curves of catalysts prepared by precipitation are significantly different from each other. Those are also very different comparing to the reduction curve of impregnated catalyst. The 20% precipitated nickel catalyst has a single peak at 540°C, but the 25% precipitated nickel catalyst shows peaks at 346°C and 503°C. The differences of peak position among the reduction curves of catalysts resulted in the differences of catalyst activities with the following order 20% Ni (impregnation) > 25% Ni (impregnation) > 20% Ni (precipitation) > 25% Ni (precipitation).   Keywords: bentonite, nickel catalyst, hidrogenation

scholarly journals Hydrogenation and Hydrodeoxygenation of Oxygen-Substituted Aromatics over Rh/silica: Catechol, Resorcinol and Hydroquinone

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 584
Author(s):  
Kathleen Kirkwood ◽  
S. David Jackson
Keyword(s):  
Hydroxyl Group ◽  
Trans Isomers ◽  
Cumulative Yield ◽  
Temperature Programmed Oxidation ◽  
Kinetic Isotope ◽  
A Value ◽  
Negative Order ◽  
Temperature Programmed ◽  
Direct Hydrogenation ◽  
Positive Half

The hydrogenation and hydrodeoxygenation (HDO) of dihydroxybenzene isomers, catechol (1,2-dihydroxybenzene), resorcinol (1,3-dihydroxybenzene) and hydroquinone (1,4-dihydroxybenzene) was studied in the liquid phase over a Rh/silica catalyst at 303–343 K and 3 barg hydrogen pressure. The following order of reactivity, resorcinol > catechol > hydroquinone (meta > ortho > para) was obtained. Kinetic analysis revealed that catechol had a negative order of reaction whereas both hydroquinone and resorcinol gave positive half-order suggesting that catechol is more strongly adsorbed. Activation energies of ~30 kJ·mol−1 were determined for catechol and hydroquinone, while resorcinol gave a value of 41 kJ·mol−1. Resorcinol, and similarly hydroquinone, gave higher yields of the hydrogenolysis products (cyclohexanol, cyclohexanone and cyclohexane) with a cumulative yield of ~40%. In contrast catechol favoured hydrogenation, specifically to cis-1,2-dihydroxycyclohexane. It is proposed that cis-isomers are formed from hydrogenation of dihydroxycyclohexenes and high selectivity to cis-1,2-dihydroxycyclohexane can be explained by the enhanced stability of 1,2-dihydroxycyclohex-1-ene relative to other cyclohexene intermediates of catechol, resorcinol or hydroquinone. Trans-isomers are not formed by isomerisation of the equivalent cis-dihydroxycyclohexane but by direct hydrogenation of 2/3/4-hydroxycyclohexanone. The higher selectivity to HDO for resorcinol and hydroquinone may relate to the reactive surface cyclohexenes that have a C=C double bond β-γ to a hydroxyl group aiding hydrogenolysis. Using deuterium instead of hydrogen revealed that each isomer had a unique kinetic isotope effect and that HDO to cyclohexane was dramatically affected. The delay in the production of cyclohexane suggest that deuterium acted as an inhibitor and may have blocked the specific HDO site that results in cyclohexane formation. Carbon deposition was detected by temperature programmed oxidation (TPO) and revealed three surface species.

scholarly journals Nickel-Catalysed Vapour-Phase Hydrogenation of Furfural, Insights into Reactivity and Deactivation

2020 ◽  
Vol 63 (15-18) ◽  
pp. 1446-1462 ◽  
Author(s):  
Kathryn L. MacIntosh ◽  
Simon K. Beaumont
Keyword(s):  
Furfuryl Alcohol ◽  
Copper Chromite ◽  
Catalyst Support ◽  
Nickel Catalysts ◽  
Vapour Phase ◽  
X Ray Diffraction ◽  
Temperature Programmed Oxidation ◽  
Acidic Sites ◽  
Supported Nickel Catalysts ◽  
Temperature Programmed

AbstractFurfural is a key bioderived platform molecule, and its hydrogenation affords access to a number of important chemical intermediates that can act as “drop-in” replacements to those derived from crude oil or novel alternatives with desirable properties. Here, the vapour phase hydrogenation of furfural to furfuryl alcohol at 180 °C over standard impregnated nickel catalysts is reported and contrasted with the same reaction over copper chromite. Whilst the selectivity to furfuryl alcohol of the unmodified nickel catalysts is much lower than for copper chromite as expected, the activity of the nickel catalysts in the vapour phase is significantly higher, and the deactivation profile remarkably similar. In the case of the supported nickel catalysts, possible contribution to the deactivation by acidic sites on the catalyst support is discounted based on the similarity of deactivation kinetics on Ni/SiO2 with those seen for less acidic Ni/TiO2 and Ni/CeO2. Powder X-ray diffraction is used to exclude sintering as a primary deactivation pathway. Significant coking of the catalyst (~ 30 wt% over 16 h) is observed using temperature programmed oxidation. This, in combination with the solvent extraction analysis and infrared spectroscopy of the coked catalysts points to deactivation by polymeric condensation products of (reactant or) products and hydrocarbon like coke. These findings pave the way for targeted modification of nickel catalysts to use for this important biofeedstock-to-chemicals transformation.

scholarly journals Effect of Ionic Liquid Surfactants on Coal Oxidation and Structure

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Weiqing Zhang ◽  
Shuguang Jiang ◽  
Tong Qin ◽  
Jianfeng Sun ◽  
Chaowei Dong ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Critical Micelle Concentration ◽  
Ammonium Chloride ◽  
Coal Oxidation ◽  
Thermal Stabilities ◽  
Oxidation Activity ◽  
Temperature Programmed Oxidation ◽  
Surface Activities ◽  
Temperature Programmed

The effects of six ionic liquids with surfactant property (1-hydroxyethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide ([HOEtMIm][NTf2]), 1-hydroxyethyl-3-methyl imidazolium tetrafluoroborate ([HOEtMIm][BF4]), 1-dodecyl-3- methyl imidazolium bromide ([C12MIm]Br), 1-tetradecyl-3- methyl imidazolium bromide ([C14MIm]Br), trioctyl methyl ammonium chloride ([N8,8,8,1])Cl, and tetraethyl ammonium chloride ([N2,2,2,2]Cl)) on the oxidation characteristics and functional groups of coal were studied by means of critical micelle concentration, surface tension, thermogravimetric analysis, temperature-programmed oxidation, and Fourier transform infrared spectroscopy (FTIR) measurements. The lower critical micelle concentration for the ionic liquids except the [N2,2,2,2]Cl suggests the favorable surface activity of these ionic liquids. The surface activities of [N8,8,8,1]Cl, [C14MIm]Br, [C12MIm]Br, and [HOEtMIm][NTf2] were high, while that of [N2,2,2,2]Cl was relatively lower. The thermal stabilities of [HOEtMIm][NTf2] and [HOEtMIm][BF4] were high, while those of [N8,8,8,1]Cl and [N2,2,2,2]Cl were lower. The oxidation activities of ionic liquid-mixed coals were weakened to different degrees except [N8,8,8,1]Cl-mixed coal, because of the poor thermal stability and decomposition of [N8,8,8,1]Cl accelerating the coal oxidation. The other five ionic liquids were suitable for inhibiting coal oxidation, particularly the [HOEtMIm][BF4] and [HOEtMIm][NTf2] with higher inhibition rate, longer inhibition time, and also better thermal stabilities. The activation energy results further confirmed such inhibition effect. The functional group results showed that treatment of ionic liquids on coal can change the contents of hydrogen bonds, aliphatic groups, and aromatic groups in coal. It was inferred that the [HOEtMIm][BF4], [HOEtMIm][NTf2], and [C14MIm]Br were more effectively to affect coal structure and decrease coal oxidation activity.

scholarly journals Development of Pre-Turbo Catalyst for Natural Gas Engines

2003 ◽  
Author(s):  
Thierry Leprince ◽  
Joe Aleixo ◽  
Kamal Chowdhury ◽  
Mojghan Naseri ◽  
Shazan Williams
Keyword(s):  
Natural Gas ◽  
Greenhouse Gas ◽  
Turbine Blades ◽  
Catalyst Design ◽  
Oxidation Catalyst ◽  
Sudden Increase ◽  
Natural Gas Engines ◽  
Exhaust Temperature ◽  
Distributed Power Generation ◽  
Conversion Efficiencies

Distributed power generation is an efficient method for reducing CO2 emissions through the elimination of transmission losses. Co-generation has similar benefits with higher thermal efficiency. Natural gas engines are very popular for these applications. Unfortunately, these engines emit significant levels of methane, which is a greenhouse gas. Reduction of methane emissions would greatly improve the environment and provide greenhouse gas emissions credits. The exhaust temperature downstream of the turbocharger in a natural gas engine is typically below 500°C. At these temperatures, methane is difficult to oxidize with current oxidation catalysts. It would be a much better option to install the oxidation catalyst before the turbocharger where temperatures are 100–150°C higher. Pressures upstream of the turbocharger are higher than downstream and also affect catalyst conversion efficiencies. Misfiring events are common in natural gas engines. During misfiring events, the catalyst will see a sudden increase in hydrocarbon (methane). When this pulse of hydrocarbon hits the catalyst, it will be oxidized and generate a large exotherm which could lead to catalyst failure (mechanical and/or chemical). This issue is critical for a pre-turbo catalyst: 1) Mechanical failure of the catalyst could lead to catastrophic turbocharger failure, a result of the turbine blades being damaged. 2) Misfiring with catalyst installed before the turbocharger is more likely to ignite the methane pulse because of the higher temperatures in this location. High exotherms from ignition could negatively affect catalyst performance. Through careful catalyst design, one can minimize this risk and this paper will address these issues.

Sign in / Sign up

Export Citation Format

Share Document