Some powders like W231 are designed to burn well at high pressure, which the 45 doesn't really generate. That is why it is smoky/dirty. It burns much better in max, high pressure loads.
As noted above, some of the best powders for the 45 are fast shotgun powders, since they are designed to burn cleanly at low pressure. These include very fast powders such as Clays, 700X, Red Dot, etc. HOWEVER, a lot of care must be taken using these very fast powders and charge weights are tiny. A double charge, or overcharge will be disastrous.
Titegroup is a slightly slower powder than the above, and a good all around powder.