Coupling reaction of CO₂ and PO^a.

Entry	[Al]/[PO]	[TBAB]/[PO]	Yieldb (%)	TOFc (h−1)
1	0.5%	0	<1	—
2	0	1%	36	—
3	0.5%	1%	62	9150
4	0.5%	3%	85	12 540
5	0.5%	5%	>99	14 700
6d	0.5%	5%	35	5160
7	0	5%	90	—

^aTypical reaction conditions: 150 °C, 2.0 MPa, [CO₂]/[PO] = 2 : 1, (CO₂ flow rate of 385 mL min⁻¹ under standard conditions and PO flow rate of 0.6 mL min⁻¹) residence time 48.8 s for entries 1–5. The propylene carbonate selectivity is >99% based on GC.

^bYield of propylene carbonate.

^cTurnover frequency (TOF) = moles of cyclic carbonate per mole of Al-catalyst per hour.

^dThe coupling reaction was performed in a conventional stirred reactor for 49 s.