Partial and Total Solvent-Free Limonene’s Hydrogenation: Metals, Supports, Pressure, and Water Effects

Table 1

Hydrogenation of limonene over Pd.

Pressure (MPa)	Support	H2O	Conversion (%)	Menthene/menthane (%)	Cis/trans menthane (%)	Time (h)	TOF (h^−1)^b	Cymene (%)
2.75	Carbon^b	—	100	0/100	19/81	2	39	61
		100 µL	100	0/100	26/74	2	39	40
		5 mL	100	78/21	20/80	4	18.5	53
		—	100	71/29	29/71	2	39	28
		100 µL	100	69/31	33/67	2	39	15
		5 mL	95	100/0	—	6	12	28
	Silica^c	—	100	100/0	—	4	19.5	14
		100 µL	100	39/61	27/73	2	39	0
		5 mL	0	—	—	—	—	—
0.275	Carbon^b	—	100	93/7	37/63	4	19.5	7
		100 µL	100	67/33	25/75	2	39	23
		5 mL	100	100/0	—	24	3.2	12
		—	100	78/18	37/63	2	39	4
		100 µL	100	91/9	40/60	2	39	6
		5 mL	85	98/2	41/59	24	2.7	44
	Silica^c	—	100	96/4	43/57	6	13	2
		100 µL	100	98/2	20/80	4	19.5	2
		5 mL	86	100/0	—	24	2.8	28

Experimental conditions: pure limonene, the catalyst, and room temperature. ^aTurnover frequency (TOF) = number of moles of consumed limonene/(mole of catalyst) time of reaction; ^b10% wt; ^c0.2 mmol/g.