Table 2. Challenges in the field of FCC catalysts and related responses.

Challenge	Response
Heavier feedstocks (resid conversion)	Improve accessibility of the matrix
	Hierarchical pore design
	Better stability to poisons
Selectivity towards propylene	Dedicated process and catalysts
	Use of new selective zeolites
Selectivity towards middle distillates	Matrix activity
	Controlled acidity in zeolite hydrocracking
Biomass conversion	Resistance to specific poisons (e.g. alkaline metals) and the high acidity of bio-oils
Tight oil conversion	Resistance to specific poisons and fracking additives