Table 1.

Experimental parameters of as-submitted datasets

Dataset	Measurement method	Gas purity (%)	Sample size (g)	Outgas condition	Sample handling/weighing and transfer
1	Manometric	CO2: 99.999%	1.182, 1.181	High-vac, evacuate at RT, ramped 1 K/min to 623 K, held at 623 K for 12 h	Activated ex-situ, then transferred air-free to sample holder in Ar glovebox
2	Manometric	CO2: 99.999% He: 99.9999%	0.659, 0.745	High-vac, ramped 1 K/min to 623 K, held at 623 K for 12 h	Activated ex-situ, transferred in air to instrument, reactivated at 623 K for 12 h using rough pump in instrument before measurement
3	Manometric	CO2: 99.998%	1.202, 1.199	Vac at RT for 4 h, ramped 2 K/min to 623 K, held for 40 h	Activated ex-situ, then transferred air-free to sample holder in N2 glovebox; once in instrument, evacuate for 2 h before measurement
4	Manometric	CO2: 99.9995%	~ 2	High-vac, evacuate at RT, ramped 1 K/min to 623 K, held at 623 K for at least 12 h	Activated ex-situ, transferred in air to instrument, reactivated at 573 K in instrument
5	Gravimetric	CO2: 99.999%	~ 0.040	High-vac (< 10− 7 kPa), ramped at 5 K/min to 623 K, held for 13.3 h	Activated in-situ
6	Gravimetric	CO2: 99.999%	0.174, 0.183	High-vac, ramped 1 K/min to 623 K, held at 623 K for 14 h	Activated in-situ
7	Manometric	CO2: 99.999%	~ 3	Under vac and He flow, ramped 1 K/min − 2 K/min to 623 K, hold overnight, increased vacuum to 0.034 kPa to eliminate any trace helium	Activated in-situ (final mass calculated based on % weight loss from gravimetric system of dataset #7)
	Gravimetric	CO2: 99.999%	0.775	Under vac and He flow, ramped 1 K/min − 2 K/min to 623 K, held for 4 h, helium vacuumed off to 2 × 10− 5 kPa	Activated in-situ
8	Manometric	CO2: 99.999%	2.231, 2.69	High-vac, 623 K for 24 h	Activated ex-situ, transferred in air/helium to instrument
9	Gravimetric	CO2: 99.999% He: 99.999%	0.81, 0.85	High-vac (< 10− 5 kPa) RT for 1 h, then ramped 1 K/min to 623 K, held for 12 h	Activated in-situ
10	Gravimetric	CO2: 99.999%	0.094, 0.095	High-vac, ramped 1 K/min to 623 K, held at 623 K for 18 h 40 min	Activated in-situ
11	Gravimetric	CO2: 99.999%	0.0675, 0.0691	High-vac (5 × 10− 11 kPa), ramped 1.2 K/min to 623 K, held at 623 K for 16 h	Activated in-situ
12	Manometric	CO2: 99.999%	1.3089, 1.147	Rough vacuum at 353 K for 1 h, ramped 1 K/min to 393 K, held 1 h, ramp 5 K/h to 623 K, held 12 h	Activated ex-situ, transferred in air to instrument
13	Gravimetric	CO2: 99.999%	~ 0.1	High-vac (< 1 × 10− 5 kPa), ramped 0.83 K/min to 423 K, then 1.67 K/min to 623 K, held at 623 K for 16 h	Activated in-situ

Dataset	Void volume/buoyancy correction	Equation of state	Temperature and stability	Pressure transducer accuracy	Blank correctiona
1	Void volume from skeletal density (from Helium pycnometry) and mass of sample	Span and Wagner (Span and Wagner 1996)	(293.15 ± 0.1) K Mb = (313 ± 0.1) K	2.07 MPa and 20.7 MPa; accuracy: ±0.05% F.S.c	yes, Si shot
2	Void volume via He expansion	Span and Wagner	(293.15 ± 0.02) K M = (294.25 ± 0.02) K	Piezo-resistive sensor with range of 133 kPa and 13.5 MPa; accuracy: ±0.04% F.S	No
3	Void volume via He expansion at 70 kPa at 298 K, average of 10 runs	Span and Wagner	(293.15 ± 0.02) K	Below 110 kPa, accuracy ± 0.15% reading; above 110 kPa, accuracy ± 0.04% F.S. (13.3 MPa) with stability of ± 0.1%	Yes, empty sample holder
4	Void volume via He expansion at 293.15 K; average of 6 runs at different pressures	Span and Wagner	(293.15 ± 0.05) K M = (294.15 ± 0.5) K	0 kPa − 133 kPa and 0 MPa–3.33 MPa pressure transducers; accuracy: not mentioned	No
5	Buoyancy correction from ex-situ determined skeletal density and mass of sample and balance components	Span and Wagner	(293.15 ± 0.05) K	6 MPa or 20 MPa; accuracy: ± 0.04% F.S	No
6	Buoyancy correction from ex-situ determined skeletal density and mass of sample and balance components	Span and Wagner	(293.15 ± 0.1) K air bath = 298 K	Below 127 kPa, accuracy 0.12% of reading with resolution of 0.002% F.S (3.33 MPa). Above 127 kPa, accuracy ± 0.04% F.S	Yes, Si shot
7	Void volume from He expansion	Virial equation (to 2nd coefficients)	(293.15 ± 0.1) K	0 kPa − 68.9 kPa (70 Pa digital readout resolution) and 0 kPa − 689 kPa (0.69 kPa digital readout resolution)	No
	Buoyancy correction from He isotherm	Simultaneously measured CO2 density from mass measurement of sinker with known mass (volume)	(293 ± 1) K	0 MPa − 1.37 MPa (digital readout resolution 133 Pa) and 0 MPa − 3.45 MPa (digital readout resolution 6.89 kPa)	No
8	Void volume via He expansion	Span and Wagner	(293.10 ± 0.02) K M = (293.10 ± 0.03) K	A piezoelectric pressure transmitter with precision of 0.01% F.S	No
9	Buoyancy correction via sample volume determined from He isotherm	Span and Wagner	(293.15 ± 0.5) K	Below 133.3 kPa, resolution 1.3 Pa 133.3 kPa to 3.333 MPa, resolution 32.5 Pa Up to 16 MPa accuracy 0.1% F.S	No
10	Buoyancy correction from ex-situ determined skeletal density and mass of sample and balance components	Span and Wagner	(293.15 ± 0.02) K	0 MPa − 2.0 MPa, accuracy ± 0.04% F.S. and resolution 0.006% F.S.; 0 kPa − 10 kPa accuracy ± 0.15% reading and resolution 0.001% F.S	Yes, Si shot
11	Buoyancy correction not applied	Not used	(293.15 ± 0.1) K	0 MPa − 2.0 MPa, accuracy ± 0.02% of range (2.0 MPa)	No
12	Not mentioned	Span and Wagner	(293.15 ± 0.01) K M = (293.15 ± 0.2) K	0.1 MPa and 20 MPa; accuracy ± 0.05% F.S	Yes, empty sample holder
13	Buoyancy correction via sample volume determined from He isotherm	Lee/Kesler Generalized-correlation method (Lee and Kesler 1975)	293.15 K	0 kPa − 1.33 kPa, 0 kPa − 13.3 kPa, 0 kPa − 133 kPa, and 0 kPa − 1.333 MPa	No

^aBlank isotherm was measured using CO₂ at 293.15 K using either an empty sample holder or a non-adsorbing sample (Si shot)

^bM = manifold or air bath temperature (temperature of reference volume or other components of instruments (not at the analysis site) involved in calculation of excess adsorption)

^cF.S. = Full Scale