During combustion process, hydrocarbons, nitrogen oxide and carbon monoxide are produced. These gases are dangerous when released to the atmosphere, so back in the 70s, a Clean Air Act was passed to limit amount of pollutants being emitted from vehicles. In response to this, auto manufacturers including the Buick added pollution control devices in their automobiles and started to use self adjusting engines.
One of the devices used to control harmful emissions is the catalytic converter. This device looks like a muffler and is a part of the exhaust system of your Buick vehicle. The use of catalytic converters has been required in US since the 1980s; however only gasoline-powered autos have catalytic converters, so diesel-powered Buicks don't have cats. It is called a "catalytic converter" because it has pellets that serve as catalyst that speed up chemical process to convert the exhaust into carbon dioxide and water, which are environment friendly.
In the engine, the air and fuel mixture are burned in order to produce power that would drive the wheels to turn. The excess burned gas is then expelled to the exhaust system, particularly in the Buick catalytic converter, so it can be turned into non-harmful emissions before they are sent out in the air. Your Buick catalytic converter is actually an extra place for the oxidation or combustion. Here, the exhaust gas is chemically oxidized with the help of the platinum-made honeycomb.
As the catalytic converter cleans the exhaust by converting it into carbon dioxide or water, it produces heat. Thus, the more harmful exhaust, the more heat it is able to produce. You probably have heard of or have seen a catalytic converter glowing, this is due to the excessive amount of heat it produces. If your Buick catalytic converter reaches this point, it is now more prone to damages. If you are using leaded fuel, your catalytic converter might fail to work because led produces coating on the platinum.