Catalytic Synthesis of Glycerol tert-Butyl Ethers as Fuel Additives from the Biodiesel By-Product Glycerol

Table 1

Characteristics of catalysts of catalysts used in this study.

Characteristics	Amberlyst 15	Amberlyst 35 dry	Amberlyst 35 wet
Physical form	Opaque beads	Opaque beads	Opaque beads
Concentration (eq/kg)	≥4.7	≥5.0	≥1.9
Surface area (m^2/g)	53	50	50
Average pore diameter (Å)	300	300	300
Total pore volume (mL/g)	0.40	0.35	0.35