Lub International Union ntawm Tshuaj thiab Siv Tshuaj Chemistry (IUPAC) txhais cov catalyst raws li ib yam khoom uas nce tus nqi ntawm cov tshuaj tiv thaiv yam tsis tau hloov tag nrho cov qauv Gibbs dawb zog hloov. Cov nyhuv no yog hu ua catalysis, thiab cov tshuaj tiv thaiv uas muaj cov catalysts hu ua catalytic reactions.
Cov khoom muaj pes tsawg leeg, tshuaj lom neeg, thiab qhov loj ntawm cov catalyst tseem tsis hloov ua ntej thiab tom qab cov tshuaj tiv thaiv; nws txoj kev sib raug zoo nrog cov tshuaj tiv thaiv kab mob zoo li lub xauv thiab qhov tseem ceeb, nthuav tawm kev xaiv siab (lossis tshwj xeeb). Lub catalyst tsis catalyze tag nrho cov tshuaj tiv thaiv; qee cov tshuaj tiv thaiv tsis xav tau ib qho catalyst.
