Catalysis is the process, not the powder. You add a catalyst — a helper substance — and a chemical change runs faster. The change would often still happen, just slowly; catalysis is the speeding-up. School books say the helper is “not used up.” Though actually it does take part, then comes back, so in the net reaction it is still there — that tidy sentence hides a messier truth. Chemists live on this word. In everyday English it is rare. People sometimes borrow it as a metaphor for a meeting that starts a change, but most speakers grab catalyst for that, not catalysis. A car's catalytic converter is the place many students meet the family first: it uses catalysis to clean the exhaust.