Table 1.

The conversion (X) and selectivity (S) obtained halfway through the first, second, and eighth cycle of the ten catalyst materials under investigation.^[a]

Catalyst material (supported on Al2O3)	Code	First cycle	Second cycle	Eighth cycle	Coke dep[b]	Darkening[c]	D/G[d]
		X [%]	S [%]	X [%]	S [%]	X [%]	S [%]	(wt %)	[%]	(−)
1000 ppm Pt, 1.5 wt % Ga, 0.25 wt % K	PtGaK	42.0	96.7	41.9	96.1	35.3	93.5	0.33	2.2	0.74
1000 ppm Pt, 3 wt % Ga, 0.25 wt % K	Pt3GaK	41.9	96.9	42.6	96.7	37.5	94.0	0.24	4.0	0.80
1000 ppm Pt, 1.5 wt % Ga	PtGa	42.0	96.7	42.6	96.8	32.3	92.8	0.55	10.8	0.84
1000 ppm Pt, 3 wt % Ga	Pt3Ga	40.3	95.4	41.3	94.6	35.0	91.9	0.52	20.6	0.73
1.5 wt % Ga, 0.25 wt % K	GaK	14.7	88.9	24.0	86.5	15.7	78.2	0.23	2.0	0.96
3 wt % Ga, 0.25 wt % K	3GaK	21.8	89.0	21.8	85.4	10.4	65.8	0.43	5.4	0.94
1.5 wt % Ga	Ga	15.8	81.3	20.4	84.8	15.3	77.4	0.34	33.5	0.98
3 wt % Ga	3Ga	20.7	88.0	23.8	88.0	12.6	75.7	0.33	12.5	1.00
1000 ppm Pt	Pt	11.5	56.4	10.3	52.1	9.2	48.5	0.44	1.1	0.64
bare alumina	Al2O3	5.5	45.5	5.9	45.8	5.6	44.7	0.46	2.3	0.78

^[a] The catalysts show somewhat higher values for conversion at the start of a dehydrogenation cycle, which then slowly drop during the 15 min cycle. The wt % of coke deposited on the catalyst material as measured by TGA, the catalyst darkening as measured by operando UV/Vis and the D/G ratio as measured by operando Raman are also included.

^[b] The coke deposited was calculated using the TGA curve with (α−β)/α^*100 %, with α being w_cat at T=300 °C, and β being w_cat at T=650 °C.

^[c] Darkening is defined as the light absorbed by the catalysts between 750 and 850 nm, relative to carbon nanofibers and the white catalyst.

^[d] Ratio of the intensities of the D and G bands obtained from the operando Raman spectra.