Catalytic devices poisoning

Catalytic Point Detection Moderate Moderate ISA CSA (API) Easily Positioned Industry Standard Detection Device Poisoning Limited to Spot Detection Costly Maintenance Expert Judgment Required for Placement Point Sources (Pumps, Compressors, Seals, etc.)... 

Deng YQ, Neved TG, Ewen RJ, Honeybonme CL, Jones MG (1993) Sulfur poisoning, recovery and related phenomena over supported padadium, rhodiinn and iridium catalysts for methane oxidation. Appl Catal A 101 51-62 Ehrhardt JJ, CoUn L, Jamois D (1997) Poisoning of platinum surfaces by hexamethyldisdoxane (HMDS) application to catalytic methane sensors. Sens Actuators B 40 117-124 Firth JG, Jones A, Jones TA (1973) The principles of the detection of flammable atmospheres by catalytic devices. Combust Flame 21 303-311... 

The catalytic converter acts as a device to speed up reactions which involve the pollutant gases, converting them to less harmful products, such as nitrogen and carbon dioxide. It should be noted that catalytic converters can only be used with unleaded petrol as the lead poisons the catalyst, preventing it from catalysing the reactions. For a further discussion of catalytic converters see Chapter 7, p. 110. 

The studies made on the Pd MIS structure have demonstrated that H2 sensors can be reliable devices, with high sensitivity and fast response. On the basis of the investigated structures and results, it has been established that the main mechanism responsible for the sensitivity is the change in contact potential. Once the a-Si H film is in some way protected from contaminating gases or liquids, MIS H2 sensor performances are mainly determined, controlled, and limited by the quality, poisoning, and stability of the Pd film or of any suitable catalytic material used. 

From these results we may understand that, surprisingly, under certain conditions that zinc could be a promoter of the platinum rather than a poison for reactions involved in a catalytic exhaust device. 

The rapid growth in demand for catalytic flammable gas sensors to operate in hostile atmospheres (leaded petrol atmospheres, gas compressor stations, etc.) and areas where routine calibration and maintenance are difficult and costly (North Sea gas and oil platforms) has stimulated the search for sensing elements which are resistant to poisons. These devices generally take the form of a platinum wire coil embedded in a porous bead comprising active catalyst either dispersed throughout a porous substrate (5-7) or as discrete layers within the substrate (8). 

The catalytic gas sensor has proven to be a most reliable and rugged means for the quantitative measurement of flammable gases in air, giving a measure of explosiveness irrespective of the composition of the gas mixture. The recent development of poison-resistant devices has overcome the problem of... 

Since lead can poison auto exhaust catalysts, automobiles equipped with catalytic exhaust-control devices require lead-free gasoline, which has become the standard motor fuel. Sulfur in gasoline is also detrimental to catalyst performance, so sulfur levels in gasoline are kept very low. 

---