Table 3. Yield of Dimethyl Adipate under Optimized Conditions for Fly Ash Catalysts^a.

entry	fly ash catalysts	% yield of dimethyl adipate
1	FS-1	98
2	FP-1	94
3	FC-1	72
4	without catalyst	55

^aReaction conditions: adipic acid: 1 mol, methanol: 6 mol, catalyst: 10% wt/wt, reaction time: 4 h, and reaction temperature: 200 °C.