High surface area and interconnected nanoporosity of clay-rich astromaterials: N2 BET and TG-DSC-MSEGA data

Whereas the bulk porosity of clay-rich meteorites is well established, the magnitude of their surface area and nano-scale porosity is poorly known. Here we apply the N2 BET gas adsorption method to measure the scale-distribution and net surface area of porosity in a range of clay-rich carbonaceous chondrite (CC) meteorites: Tarda (C2-ung), Ivuna (CI1), Orgueil (CI1), Aguas Zarcas (CM2), and Murchison (CM2). For comparison, N2 BET data was also acquired from the anhydrous CC Allende (CV3). Tarda (C2-ung) has high surface area, up to 82 m2/g, dominated by an interconnected network of ~3-nm-sized pores. In comparison, Ivuna and Orgueil (CI1) and Aguas Zarcas and Murchison (CM2) have bimodal nanopore-size distributions with a lower density of ~3-nm pores and broader size distributions around 40 nm, and corresponding lower surface areas ~14-19 m2/g. A summary of the data is shown in Table 1 (file 2Table1 N2BET data CC meteorites.docx).

Two data sets are included that accompany the paper entitled "High surface area and interconnected nanoporosity of clay-rich astromaterials": the raw N2 BET data files including the derivation of the pore size and pore-size distribution; and the TG, DSC, and MSEGA data for the unweathered and artificially weathered Tarda meteorite.

Prior to the N2 BET measurements, it is necessary to remove these physisorbed species through outgassing. The N2 BET measurements were acquired after several outgassing pretreatment - the pretreatment is listed after the meteorite name: Tarda-100 refers to the sample outgassed at 100 °C under flowing N2 for 24 hr; after prolonged storage under a dry N2 atmosphere (-NH); after being held under a vacuum for 24 hr at room temperature (-VRT); and, after heating in the presence of flowing dry nitrogen at 250 °C for 24 hr (-250) (Table 1). The N2 BET measurements are made by exposing the degassed sample to N2 at a series of controlled pressures while maintaining the sample at a constant cryogenic temperature of -195.8 °C, which corresponds to the boiling point of N2. The volume of adsorbed or desorbed gas is measured over a relative equilibrium adsorption pressure (p/p0) from near 0 to 1, where p is the absolute equilibrium pressure and p0 the saturation pressure of the gas.

The Tarda N2 BET data shows the ease with which atmospheric moisture can adsorb onto its high surface area. This magnitude of the adsorption under laboratory conditions is measured by TG-DSC-MSEGA.

Further information on the data acquisition and the samples is provided in the attached file 1Materials and Methods - N2BET, TG, DSC, MSEGA.doc

尽管富黏土陨石的体孔隙度已得到充分证实，但其表面积与纳米级孔隙度的规模仍鲜有研究。本研究采用N₂ BET（Brunauer-Emmett-Teller）气体吸附法，对一系列富黏土碳质球粒陨石（carbonaceous chondrite, CC）的孔隙尺度分布与净比表面积进行测量，样品包括塔达（Tarda, C2-ung）、伊夫纳（Ivuna, CI1）、奥尔盖尔（Orgueil, CI1）、阿瓜斯·萨斯卡斯（Aguas Zarcas, CM2）以及默奇森（Murchison, CM2）。为便于对比，本研究同时对无水碳质球粒陨石阿连德（Allende, CV3）开展了N₂ BET测量。

塔达陨石的净比表面积可达82 m²/g，其孔隙以约3 nm的互联网络为主。相较之下，伊夫纳、奥尔盖尔（CI1型）以及阿瓜斯·萨斯卡斯、默奇森（CM2型）的纳米孔隙呈双峰分布：约3 nm的孔隙密度较低，孔隙尺寸分布在40 nm附近更宽，对应净比表面积约14~19 m²/g。数据汇总见表1（详见文件2Table1 N2BET data CC meteorites.docx）。

本数据集配套收录于题为《富黏土天体物质的高比表面积与互联纳米孔隙结构》的论文，包含两类数据：一是原始N₂ BET数据文件，涵盖孔隙尺寸及孔隙尺寸分布的推导过程；二是未风化与人工风化塔达陨石的TG、DSC及MSEGA数据。

开展N₂ BET测量前，需通过脱气去除样品表面的物理吸附物种。本次N₂ BET测量基于多种脱气预处理方案，预处理方式标注于样品名称之后：Tarda-100指样品在流动N₂气氛下100℃脱气24小时；-NH指经干燥N₂气氛长期储存后；-VRT指室温真空静置24小时后；-250指在流动干燥N₂气氛下250℃加热24小时后（详见表1）。N₂ BET测量通过将脱气后的样品置于恒定低温（-195.8℃，即N₂的沸点）环境中，使其暴露于一系列可控分压的N₂中完成。测量覆盖相对平衡吸附压力（p/p₀，其中p为绝对平衡压力，p₀为气体饱和压力）从接近0至1的区间，以此测定气体吸附或脱附体积。

塔达陨石的N₂ BET数据表明，其高比表面积极易吸附大气水汽。实验室条件下的吸附强度通过TG-DSC-MSEGA进行测定。

关于数据采集与样品的更多细节，详见附件文件1Materials and Methods - N2BET, TG, DSC, MSEGA.doc