223 results about "Catalyst degradation" patented technology

A system for determining a reagent solution quality indicator includes a reagent solution source for supplying the reagent solution to an emissions catalyst configured to receive a NOx-containing gas therethrough, means for determining a flow rate of NOx reduced from the gas by the catalyst, means for determining a flow rate of the reagent solution into the catalyst, and a control circuit determining the reagent solution quality indicator as a function of the NOx flow rate and the reagent solution flow rate. The system may additionally be configured to diagnose reagent solution quality by configuring the control circuit to monitor the reagent solution quality indicator over time and produce a fault value if the reagent solution quality indicator crosses a reagent quality indicator threshold, and to diagnose the catalyst by producing another fault value if the catalyst capacity point falls outside of a catalyst capacity point threshold.

This invention relates to a process for the selective alkylation of toluene and / or benzene with an oxygen-containing alkylation agent. In particular, the process uses a selectivated molecular sieve which has been modified by the addition of a hydrogenation component, wherein at least one of the following conditions is met: (a) the selectivated molecular sieve has an alpha value of less than 100 prior to the addition of the hydrogenation component, or (b) the selectivated and hydrogenated catalyst has an alpha value of less than 100. The process of this invention provides high selectivity for the alkylated product while reducing catalyst degradation.

A catalyst degradation determining method includes the steps of: controlling an upstream-of-catalyst air-fuel ratio occurring upstream of a first catalyst to an air-fuel ratio that is rich of a stoichiometric air-fuel ratio so that first and second catalysts store oxygen up to a maximum storage amount of oxygen. The method then includes the steps of controlling the upstream-of-catalyst air-fuel ratio to a first lean air-fuel ratio until an output of a downstream-of-first-catalyst sensor indicates a lean air-fuel ratio, and then to a second lean air-fuel ratio and that has a value that is determined in accordance with an oxidizing-reducing capability index value, until a time point when an output of a downstream-of-second-catalyst air-fuel ratio sensor indicates an air-fuel ratio that is lean.

The invention relates to a system and method for detecting low quality reductant and catalyst degradation in selective catalytic reduction systems, in particular, a control system for a selective catalytic reduction (SCR) system includes a conversion efficiency determination module, an ammonia slip determination module, and a diagnostic module. The conversion efficiency determination module determines a conversion efficiency of an SCR catalyst. The ammonia slip determination module determines an amount of ammonia slip across the SCR catalyst when the conversion efficiency is less than a predetermined threshold. The diagnostic module determines pass / fail statuses of a reductant supply and the SCR catalyst based on the amount of ammonia slip and at least one ammonia slip threshold.

A process of stabilizing an olefin metathesis product mixture, preferably, against double bond isomerization and thermal and chemical degradation. The process involves (a) contacting an olefin metathesis product mixture comprising one or more olefins produced in a metathesis process, a metathesis catalyst comprising a catalytic metal and one or more ligands, optionally, one or more metathesis catalyst degradation products, and optionally, one or more metals derived from sources other than the catalyst or catalyst degradation product(s), with an adsorbent, more preferably carbon; or alternatively, (b) subjecting the olefin metathesis product mixture to a two-step distillation, preferably, including short path wiped-film evaporation. A stabilized olefin metathesis product mixture is disclosed containing one or more olefins obtained in a metathesis process and having a total concentration of metal(s) of less than about 30 parts per million by weight.

The invention discloses a device and a method for treating antibiotic wastewater by utilizing low temperature plasma in coordination with a bismuth molybdate catalyst. The device for treating the antibiotic wastewater by utilizing the low temperature plasma in coordination with the bismuth molybdate catalyst comprises a barrel-shaped reactor, a breather pipe, a high voltage electrode, an alternating current high voltage power supply, an air pump and a stirrer, wherein the breather pipe is arranged inside the barrel-shaped reactor and is coaxial with the barrel-shaped reactor, the high voltage electrode is suspended inside the breather pipe, the lower port of the breather pipe is arranged at the lower bottom part inside the barrel-shaped reactor, the upper part of the breather pipe is arranged outside the barrel-shaped reactor, an air inlet is formed in the side wall of the upper part of the breather pipe, the air inlet is communicated with the outlet of the air pump by virtue of a pipeline; the alternating current high voltage power supply is respectively connected to the high voltage electrode and grounded, and the stirrer is arranged at the lower part of the barrel-shaped reactor. The device for treating the antibiotic wastewater by utilizing the low temperature plasma in coordination with the bismuth molybdate catalyst has the characteristics of simple design, low equipment investment and no secondary pollution and can be applied to the filed of treatment on antibiotic wastewater and organic wastewater difficult to be biochemically degraded, wherein a degradation reaction temperature can be increased by fully utilizing heat produced in a discharge process.

The invention provides preparation of a magnetic heterogeneous light Fenton catalyst. The preparation comprises the following steps of: preparing mixed solution by using ferric trichloride and nickel sulfate as raw materials, and performing heating, separation, washing and drying on the mixed solution to obtain the magnetic heterogeneous light Fenton catalyst NiFe2O4. The invention also provides a method for degrading organic pollutants by using the magnetic heterogeneous light Fenton catalyst. The method for degrading the organic pollutants comprises the following steps of: placing organic pollutant solution into a reaction container; adding a proper amount of oxalic acid into the reaction container; adding a proper amount of magnetic heterogeneous light Fenton catalyst into the reactioncontainer; and performing photocatalysis reaction under the irradiation of visible ultraviolet light. The magnetic heterogeneous light Fenton catalyst NiFe2O4 improves the utilization rate of sunlight; and the magnetic heterogeneous light Fenton catalyst has good effect on nickel ferrite photocatalysis of the organic pollutants and high degradation rate.

When both catalyst degradation and catalyst odor need to be suppressed when a fuel cut condition is satisfied, a fuel cut control is executed giving priority to control for suppressing catalyst odor, though a required air amount G* for idling is drawn in at that time. Therefore, when shifting the engine into an idle state to suppress catalyst degradation after the catalyst odor has been eliminated, the required air amount G* for idling is already being drawn in so there is no need to adjust the air amount. As a result, there is no time delay for air amount adjustment. Therefore, after the control to suppress catalyst odor has ended, a smooth shift can be made into control to suppress degradation of the exhaust gas control catalyst.