This study represents the first assessment of CO storage potential in Austrian coal seams. Coal samples were taken from Fohnsdorf and Leoben abandoned coal mines, with particular emphasis on the Fohnsdorf coal since Leoben coal reserves were largely mined during previous coal production. Several methods were used to compare coal characteristics, including Rock-Eval pyrolysis (RE), organic petrography, and low-pressure N and CO sorption measurements. Both Fohnsdorf and Leoben coal samples show low sulfur and ash yields, as well as correspondingly high total organic carbon (TOC) contents. The pyrolysis T and vitrinite reflectance values agree with a low coal rank for both sites. According to the N adsorption measurements at 77 K, low-lying mire coals from Fohnsdorf show a higher BET-specific surface area (BET-SSA) and BJH pore volume compared to raised-mire coals from Leoben. However, sapropelic shales and high-ash coals from Leoben show the highest BET-SSA and BJH pore volumes of all investigated samples and considerably exceed the N adsorption volumes of pure coals from both locations (N uptake up to 16 cm/g; avg. for all samples 5.4 cm/g). In contrast, the mean adsorbed CO uptake measured at 273 K and ∼ 1 bar followed the order of Fohnsdorf low-lying mire coals > Leoben raised-mire coals > Leoben sapropelic coals and shales, ranging at ∼0.8 mmol/g, ∼0.7 mmol/g, and ∼ 0.2 mmol/g, respectively. This shows that BET-SSA and BJH equations did not allow for adequate estimation of CO adsorption capacity trends in the investigated sample set. Furthermore, based on the existence of a hysteresis loop between CO adsorption and desorption branches for all investigated samples, the occurrence of weak chemisorption phenomena during CO adsorption is indicated. This effect helps to increase CO uptake and storage safety since the chemisorption process is not fully reversible upon pressure decrease. Ultimately, the theoretical CO sequestration potential of the remaining unmined Fohnsdorf coal reserves was estimated at 4.65 million tons, with an additional potential for enhanced coal bed methane production due to the gas-rich nature of Fohnsdorf coals with an estimated 1.2 billion m of CH in place.

中文翻译：

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从废弃矿井到碳汇：评估奥地利低阶煤矿的二氧化碳储存能力

这项研究是对奥地利煤层二氧化碳储存潜力的首次评估。煤炭样本取自 Fohnsdorf 和 Leoben 废弃煤矿，特别关注 Fohnsdorf 煤炭，因为 Leoben 煤炭储量大部分是在以前的煤炭生产过程中开采的。使用了多种方法来比较煤炭特性，包括岩石评估热解 (RE)、有机岩相学以及低压 N 和 CO 吸附测量。 Fohnsdorf 和 Leoben 煤样均显示出较低的硫和灰分产量，以及相应较高的总有机碳 (TOC) 含量。热解温度和镜质体反射率值与两个地点的低煤级一致。根据 77 K 下的 N 吸附测量，与来自 Leoben 的高位泥煤相比，来自 Fohnsdorf 的低洼泥煤显示出更高的 BET 比表面积 (BET-SSA) 和 BJH 孔体积。然而，莱奥本的腐泥页岩和高灰分煤显示出所有研究样品中最高的 BET-SSA 和 BJH 孔隙体积，并且大大超过了两个地点纯煤的 N 吸附体积（N 吸收高达 16 cm/g；平均所有样品均为 5.4 厘米/克）。相比之下，在 273 K 和 ∼ 1 bar 下测得的平均吸附 CO 吸收量的顺序为 Fohnsdorf 低洼泥煤 > Leoben 高地泥煤 > Leoben 腐泥煤和页岩，范围为 ∼0.8 mmol/g、∼0.7 mmol /g，和~0.2mmol/g，分别。这表明 BET-SSA 和 BJH 方程无法充分估计所研究样品组中的 CO 吸附容量趋势。此外，基于所有研究样品的 CO 吸附和解吸分支之间存在滞后环，表明 CO 吸附过程中出现弱化学吸附现象。这种效应有助于提高二氧化碳的吸收和储存安全性，因为化学吸附过程在压力降低时并不完全可逆。最终，剩余未开采的 Fohnsdorf 煤炭储量的理论 CO 封存潜力估计为 465 万吨，由于 Fohnsdorf 煤炭富含气体的性质，估计有 12 亿立方米的 CH 存在，因此还有增加煤层气产量的额外潜力。地方。