What are examples of anti-catalyst substances?

Answer 1

they are inhibitors of chemical reactions or diminishes the activity of a catalyst. The inhibition is temporary when the poison is adsorbed on the surface of the catalyst in preference to the reactants. The Permanent poisoning is when a covalent bond is formed between the poison and the catalyst.

for example volatile sulfur and volatile silicon cause permanent poisoning during many cases. Arsenic are poison to platinum. In the reaction of decomposition of H2O2 by platinum, HCN act as poison. In another case CO act as poison to copper during the reaction of hydrogen and ethylene.