Probe for measuring sulfur content in fuel or engine exhaust has membrane separating working electrode from reference electrode on reference material

摘要

A probe has a working electrode (10) contacting a liquid to be analyzed, a reference electrode (6) isolated from the liquid and a liquid impermeable membrane (4) between them. A reference material contacts or forms the reference electrode. Ions that can chemically react with sulfur compounds in the liquid can pass through the electrode Independent claims are included for the following: (a) Apparatus has probes as above both upstream and downstream of an adsorber in a fuel line Comparison of the signals from the probes measures the level of sulfur in the adsorber. (b) Apparatus has probes upstream and downstream of an adsorber in a fuel line. A reference electrode of the downstream probe contacts the untreated fuel upstream of the adsorber. (c) Apparatus has a probe as above measuring the level of sulfur in an adsorber in a fuel line. The working electrode contacts the fuel upstream of the adsorber and the reference electrode contacts the fuel downstream of the adsorber. (d) Use of the above probe to determine the amount of sulfur in a NOx trap in an engine exhaust purification system. The engine is a petrol engine using a lean mixture. Preferred Features: The reference electrode is made from an ion that can be oxidized and can permeate the membrane. The reference material is a liquid with a specified sulfur concentration. The membrane is impermeable to fuels, e.g. petrol, diesel, heating oil, liquefied fuel gas, methanol and ethanol. A third electrode is on the membrane and a voltage is connected across it and the working electrode.