This mod includes some changes to oil refining and chemistry.

It adds a basic oil refinery, made by Deadlock989. You can get the original mod here. It only does basic oil processing, and you unlock the classic oil refinery once you unlock advanced oil processing. The oil refinery recipe has been changed so that it costs 3 basic oil refineries, and the basic oil refinery has half the cost of the original one.
All refining and cracking recipes now require steam instead of water. The original mod for that was made by Degraine, and you can download it here.

There is a new "catalyst" item, which is used to increase the reaction rate of most chemistry recipes. It functions almost exactly like a speed module, except it provides no extra energy consumption and is a bit limited. The graphics come from Public Domain Files.
Petroleum gas must be refined even further before it can be turned into useful products. You must refine it into ethylene and sulfur. Ethylene can be used for plastic, which is also a component in the new catalyst.