The Global Heat Flow Database: Release 2021

This data publication contains the compilation of global heat-flow data by the International Heat Flow Commission (IHFC; http://www.ihfc-iugg.org/) of the International Association of Seismology and Physics of the Earth's Interior (IASPEI). The presented data release 2021 contains data generated between 1939 and 2021 and constitutes an updated and extended version of the 2012 IHFC database release (IHFC 2012; later re-published as PANGAEA release: Global Heat Flow Compilation Group, 2013). The 2021 release contains 74,548 heat-flow data from 1,403 publications. 55% of the reported heat-flow values are from the continental domain (n ~ 40,870), while the remaining 45% are located in the oceanic domain (n ~ 33,678). The data are provided in csv and Excel formats. Compared to earlier compilations, which followed the structure defined by Jessop et al. (1976), the new data release was transformed to the recently redefined structure for reporting and storing heat-flow data in the Global Heat Flow Database (Fuchs et al., 2021). Therefore, the notation and structure of the database was adopted, transforming the database field entries defined after Jessop et al. (1976) to the new field structure. Old code notations are not continued and the dataset was cleaned for entries without reporting any heat-flow value. Although successfully transformed, this release marks an intermediate step as the majority of the newly defined database fields have not been filled yet. Filling these fields, checking the existing entries and assessing the quality of each entry are the aim of the upcoming Global Heat Flow Data Assessment Project, for which this data set provides the basis. Consequently, we kindly ask the user to take notice that the current release still suffers similar problems as previously published compilations in terms of data heterogeneity, documentation and quality

Synthesis of ZSM‑5 Zeolites with Defined Distribution of Al Atoms in the Framework and Multinuclear MAS NMR Analysis of the Control of Al Distribution

Sets of ZSM-5 zeolites with different distributions of Al atoms in the framework were synthesized from the mixtures of Si/Al_gel 25–90, varying in the sequence of mixing and using Na-silicate or tetraethoxy orthosilicate as the Si source, AlCl₃ or Al­(NO₃)₃ as the Al source, NaCl or Na-silicate as the Na source, and tetrapropylammonium hydroxide as the structure directing agent. The distribution of Al atoms in the ZSM-5 framework between single Al atoms and Al pairs of Al–O–(Si–O)₂–Al sequences was monitored by the ²⁹Si MAS NMR, Co­(II) ion exchange capacity and UV–vis spectroscopy of bare Co­(II) ions in the dehydrated zeolites. The results showed that the distribution of Al atoms in the ZSM-5 framework can be controlled in a wide range of concentrations (6–66% of Al atoms in Al pairs for the given Si/Al) and Si/Al_prod 15–37. From the analysis of both the initial gels and crystalline products by the ¹³C, ²⁷Al, and ²⁹Si (SP and CP) MAS NMR and FTIR, it was concluded that the electrostatic and van der Waals interactions, governed mainly by the presence of hydrophobic (TPA⁺) and charged (Na⁺) cations and anions (Cl^–, NO₃^–) of different polarization ability and by the reactivity of alumosilicate species, control the incorporation of Al atoms into the framework of ZSM-5 in the Al pairs located in the rings of three cationic sites and distant not-cooperating single Al atoms in different rings. The high concentration of Al pairs in the zeolite can be reached by the increase of the positive charge of the central N atom of TPA⁺, which supports incorporation of the Al pair in its close vicinity or by the increase in relative concentration of entities containing Al pairs in the synthesis gel. The predominant incorporation of single Al atoms into the framework occurs in the presence of highly reactive q³ Al species containing an OH group or under the addition of Na⁺ ions to the synthesis mixture. Single AlO₄^– balanced by Na⁺ ions can be located at each framework T site, not only in the vicinity of TPA⁺