In order to separately evaluate an influence degree of fuel and an influence degree of lubricating oil with respect to particulate matters contained in exhaust gas, an exhaust gas analysis method includes: analyzing particulate matters contained in the exhaust gas exhausted from an engine, thereby making it possible to analyze the particulate matters derived from the lubricating oil by using isooctane as a fuel.

A sulfur oxide detection system includes an element part which includes a sensor cell and a diffusion regulating layer. The sensor cell includes a solid electrolyte layer, a first electrode arranged, and a second electrode. The sulfur oxide detection system also includes a voltage application circuit configured to apply a voltage to the sensor cell so that a potential of the second electrode becomes higher than a potential of the first electrode, and a current detection circuit configured to detect a current flowing between the first electrode and the second electrode. The sulfur oxide detection system further includes a controller coupled with the voltage application circuit and the current detection circuit, and configured to estimate a sulfur oxide concentration in a gas to which the first electrode is exposed by way of the diffusion layer.

A control apparatus and a control method for an internal combustion engine of the present invention integrates an operating time in a state in which temperature TCAT of an exhaust gas purification catalyst is lower than a first temperature, to obtain first integrated time IT1, senses oxygen storage capacity OSC of the exhaust gas purification catalyst, and has a regeneration treatment of sulfur poisoning carried out when first integrated time IT1 exceeds first time THT1 and oxygen storage capacity OSC falls below first capacity OSC1, and furthermore, integrates an operating time in a state in which temperature TCAT of the exhaust gas purification catalyst is higher than second temperature TCAT2, to obtain second integrated time IT2, and has a regeneration treatment of oxidation poisoning carried out when second integrated time IT2 exceeds second time THT2.

A SOx concentration acquiring apparatus of an internal combustion engine of the invention acquires sensor currents as SOx concentration currents after a sensor voltage reaches an oxygen decreasing voltage in a reoxidation voltage decreasing control, acquires the sensor current as a base current when the sensor voltage is equal to or lower than the oxygen decreasing voltage in the reoxidation voltage decreasing control, acquires an integration value of differences between the base current and each of the SOx concentration currents, and acquires a SOx concentration of an exhaust gas discharged from an internal combustion engine on the basis of the integration value.

A SOx concentration acquiring apparatus of the invention comprises a sensor cell, a diffusion-limited layer, and an interior space. The sensor cell is formed by a solid electrolyte layer and sensor electrodes provided on opposite surfaces of the solid electrolyte layer, respectively. The interior space is defined by the solid electrolyte layer and the diffusion-limited layer such that an exhaust gas of an internal combustion engine flows into the interior space through the diffusion-limited layer. The apparatus executes a first voltage control for increasing and decreasing a voltage applied to the sensor cell and then, a second voltage control for increasing and decreasing the voltage. The apparatus acquires a current flowing through the sensor cell while the apparatus decreases the voltage in the second voltage control and acquire a SOx concentration of the exhaust gas on the basis of the acquired current.

A control apparatus for an internal combustion engine is provided. The control apparatus includes a temperature sensor and an electronic control unit. The temperature sensor is configured to detect the temperature of an exhaust gas control apparatus. The electronic control unit is configured to: estimate a sulfuric compound accumulation amount on the exhaust gas control apparatus; and when a specific condition in which the sulfuric compound accumulation amount is equal to or larger than a predetermined accumulation amount and the temperature of the exhaust gas control apparatus is equal to or higher than a predetermined temperature or more is satisfied, control an intake air amount adjuster such that an intake air amount when the specific condition is satisfied is increased as compared to the intake air amount when the specific condition is not satisfied in the same operation state.

An SOx index acquisition apparatus for an internal combustion engine includes a sensor cell, a voltage source. The sensor cell includes a solid electrolyte and a pair of electrodes disposed so as to sandwich the solid electrolyte. The voltage source applies a voltage to the sensor cell. The apparatus acquires a resistance value of the sensor cell as a sensor resistance, decreases an applied voltage, which is a voltage that is applied to the sensor cell, from a predetermined voltage, acquires a current that passes through the sensor cell while the applied voltage is being decreased from the predetermined voltage, as an SOx sensor current, acquires a base SOx concentration, which correlates with an SOx concentration in exhaust gas, based on parameters including the SOx sensor current, and acquires the SOx concentration as an SOx index by correcting the base SOx concentration based on the sensor resistance.

A control device of an exhaust sensor comprises a cell temperature detecting part detecting a temperature of the electrochemical cell, a heater control part controlling the heater so that a temperature of the electrochemical cell becomes the target temperature, and a judging part judging whether a water repellency of the protective layer is falling. The judging part judges that the water repellency of the protective layer is falling if a condition for judging abnormality is satisfied. The condition for judging abnormality includes a temperature of the electrochemical cell detected by the cell temperature detecting part falling from the target temperature and a speed of fall of the temperature being faster than a speed of fall of the temperature of the electrochemical cell when the heater is turned off.

An aftertreatment system comprises a SCR system including a catalyst formulated to decompose constituents of an exhaust gas passing therethrough. A filter is positioned upstream of the SCR system. The filter comprises a sulfur suppressing compound formulated to reduce an amount of SOx gases included in the exhaust gas flowing through the aftertreatment system. In particular embodiments, the filter comprises a filter housing and a filter element positioned within the filter housing. The filter element comprises the sulfur suppressing compound.

Gas treatment systems and processes for reducing tail gas emissions such as SO.sub.2, SO.sub.3, H.sub.2SO.sub.4, NOx, HC, CO, and other pollutants are provided. The processes include transferring tail gas from at least one source of tail gas to at least one destination sulphuric acid plant via a tail gas transfer system, wherein the tail gas replaces or supplements one or more of the combustion gas, air feed, dilution gas, and quench gas used by the destination sulphuric acid plant. The systems include at least one destination sulphuric acid plant and a tail gas transfer system for transferring tail gas from at least one source of tail gas to the at least one destination sulphuric acid plant. The systems and processes described herein may be used to eliminate start-up emissions and/or convert sulphur-containing species present in tail gas emissions into commercial H.sub.2SO.sub.4.