IZA-CC Test Reaction

The protolytic cracking of n-pentane and n-heptane were conducted in a tubular flow reactor with a quartz tube with an internal diameter of 7 mm at ambient pressure. Catalyst pellet (300 - 500 µm) were activated in situ at 813 K with a heating ramp of 10 K min^-1 for 1 h in 20 ml min^-1 synthetic air and then flushed for 30 min with 20 ml min^-1 N2. The reactant stream was introduced into the reactor via an evaporator, using N2 as a carrier gas. The reaction was carried out between 733 and 793 K. The molar ratio between N2 and n-heptane was kept at 100. Reactant and products were separated and analysed by on-line chromatography (Superlco Q-Plot, capillary column: 30 m × 0.53 mm × 2.0 µm) using an FID detector.

Pathway	TOF^* (mmol·mol_BAS^-1·s^-1)			Apparent activation energy (kJ·mol^-1)	Apparent activation entropy (J·mol^-1·K^-1)
Pathway	753 K	773 K	793 K	Apparent activation energy (kJ·mol^-1)	Apparent activation entropy (J·mol^-1·K^-1)
C1 + C6⁼	0.039	0.075	0.13	155	-77
C2 + C5⁼	0.060	0.10	0.17	129	-107
C3 + C4⁼	0.063	0.10	0.18	130	-106
C4 + C3⁼	0.10	0.20	0.33	149	-76
C5 + C2⁼	0.084	0.16	0.28	148	-79
Overall cracking	0.35	0.63	1.1	143	-74
Dehydrogenation^*	0.10	0.24	0.43	177	-38

^*Calculation of TOF based on yield of alkane in each pathway, assuming that all the produced alkanes do not crack.
^*Dehydrogenation quantified by the total hydrogen balance.

Notes

The overall apparent activation energy of 143 kJ/mol and the estimated heat of adsorption of 61 kJ/mol on the FAU sample lead to a true activation energy of 204 kJ/mol, well in agreement with previous experiments. Similarly, the true energy of activation (238 kJ/mol) is on the high side, but within the limits of previously reported data.

Data 2. provided by Keiichi Tomishige Group

Catalysis experiments

n-heptane (Wako, > 99 %) was used as the reactant. The catalytic cracking of n-heptane was carried out in a continuous flow fixed bed reactor. Nitrogen was used as a carried gas. Each reaction condition was listed in the supplementary part. A syringe pump was used for the feeding of n-heptane. Both of USY (IRZ-FAU001) and ZSM-5 (IRZ-MFI001) were pressed, crushed and sieved to 150-250 μm granules and then a 15-100 mg catalyst was loaded and sandwiched by two layer of silica wool in the reactor (The diameter of glass pipe was 4 mm). Depended on the type of catalysts, the heights of catalyst bed of 50 mg USY and ZSM-5 were 9mm and 7mm, respectively. Before reaction, the catalyst was pretreated in a 50 ml/min nitrogen stream at 813 K for 1 h and then was cooled down to the reaction temperature 773 K. In the activity test, n-heptane conversion at 5 min after introduction the reactant to the catalyst bed was measured as initial conversion and reaction was carried for 90 min. The mole ratio between nitrogen and n-heptane was kept at 100.
The unreacted n-heptane at reactor outlet was analyzed using gas chromatograph (GC-2025, Shimadzu) equipped with an FID detector using a capillary column (DB-35), one of the products methane was analyzed using a GC-14B equipped with FID detector (Gaskuropack 54) and other gaseous products (C2, C3 C4) were analyzed by GC-14 equipped with TCD detector (Unipak S).
The conversion, selectivity and carbon balance were calculated by flowing substrate (Flow_i) and defined by following equations:
Conversion = Σα_i×Flow_product-i / (Σα_i×Flow_product-i+7×Flow_{n-heptane-out});
Selectivity_product-i = α_i×Flow_product-i/Σα_i×Flow_product-i;
Carbon balance = (α_i×Flow_product-i+7×Flow_{n-heptane-out})/(7×Flow_n-heptane-in);
Reaction rate was based on formation rate of products:
Rate = Σ×Flow_product-i

W/F g·h·mol^-1	Conversion %	Selectivity / %								Rate mmol·min^-1
W/F g·h·mol^-1	Conversion %	CH₄	C₂H₆	C₂H₄	C₃H₈	C₃H₆	iso-C₄H₁₀	n-C₄H₁₀	C₄H₈	Rate mmol·min^-1
0.24	0	0	0	0	0	0	0	0	0	0
0.36	0	0	0	0	0	0	0	0	0	0
0.48	0.5	0	47.9	0	58.6	0	0	0	0	5.2×10^-4