Project ID:
PARTNERSHIP PNCDI-2   72196/2008                                                                                      Acronym: STOHICO                                                                                                                                    Project Director:
Dr. Petru Palade
Project Type:
National
Project Program:
Partnerships - PNCDI-2
Funded by:
Romanian National Authority for Scientific Research, UEFISCDI
Contractor:

National Institute of Materials Physics

Project summary

The project promotes and develops technologies capable to generate innovative mixed complex hydrides with very good storage properties mainly due to the special microstructure but also due proper compositions. A demonstrative hydride tank, which exploit the new materials properties, will be built and special designed for mobile (vehicular) applications. The project subscribes to the general tendency concerning the pollution and greenhouse effect diminishing. The main activity concerns the synthesis of a conglomerate/ mixture of new complex hydrides having special microstructure and in consequence optimized storage properties. Metal hydrides (FeTiH₂, LaNi₅H₆, Ti-Cr-V-H) work at room temperature, but the reversible absorbed/desorbed (abs/des) hydrogen content by weight (wt%) is very low (<2 wt% H₂) whereas  the classical complex hydrides with catalysts additions (NaAlH₄/ 2 mol% TiCl₃) can reach a reversible storage of 4,5 wt% at 150 ⁰C.The project envisages the synthesis of a material, based on mixture of complex hydrides, which contains at least 6 wt% hydrogen content by weight and the H₂ release temperature in the range of 200-230⁰C. Taking into account the previous experience of the teams and based on the most recent literature data, the most promising systems are: (i) mixtures boranates/ metal hydrides (with more than 10 wt% H­₂), in what case the aim is to decrease the H₂ release temperature (now of about 400⁰C) (ii) amides/ metal hydrides mixtures, in which case by suitable mixtures (complex systems) will increase the hydrogen content by weight (now of about 5.5 wt%). The project aims to find alternate procedures for the optimization of the new compositions/ compounds in the different processing states for the material types which will lead both to decreasing the H₂ release temperature for boranates/ hydrides mixtures and to increase the content of hydrogen stored reversibly by amides / hydrides mixtures. Very recent preparation routes will be used for these materials: impregnation from hydride solutions into light mesoporous matrix (functionalized support), co-impregnation of the mixed hydride solutions together with catalyst, co-milling of the insoluble hydrides together with soluble hydrides impregnated on supports – a sum of technologies used in premiere for hydrogen storage materials, for multilayers deposition mixing at almost molecular level the boranates/ hydrides mixtures (much better than one achieved by mechanical attrition). This will generate the decrease of the kinetic barriers for the solid state heterogeneous reactions (between the two components of the mixture) from which H₂ is generated and implicitly the diminishing of the hydrogen releasing temperature.  New type of materials (of complete novelty) will be prepared: boranates of Ca and Mg modified with transitional metals (TM), mixed boranates as Li-(TM, Si, Al) and mixed systems boranates/hydrides/Si or amides/hydrides/Si with more than 7.5 wt% H₂ and decomposition temperatures around 200 ⁰C. Quantum chemical calculations will be used for the prognosis of new materials stability and for the optimization of the compositions hydrides/ mesoporous supports. Another complete novelty is the study/control of simultaneous mechanisms: physical adsorption (on supports)/ chemical absorption (in hydrides) with possible increase of the H₂ storage capacity. As a corollary of the main direction, finally is settled the design and realization of a demonstrative tank containing about 100 g of complex hydride which will valorize the improved storage properties (> 6 wt% H₂ at 200-230 ⁰C) of the optimized material. The demonstrative tank will have automatic control of the temperature and the hydride will be dispersed into a metallic foam (which helps the thermal conduction). The demonstrator will consider also functionality tests of the hydride tank concerning fuel cell feeding with hydrogen.

Main objective: Design and synthesis of a hydrogen storage material with improved properties  (> 6 wt% H₂ at 200-230 ⁰C). There will be envisaged mixtures of boranates/metal hydrides and amides/metal hydrides prepared either by ball milling and by impregnation from hydride solutions into lightweight mesoporous supports. Quantum chemical calculations will be used for the prognosis of new materials stability and for the optimization of the hydrides impregnated into mesoporous supports. The optimized storage material will be used to build a small demonstrative hydride tank.

Specific Objectives:

O1: Thermodynamic stability calculations for boranates/hydrides and of the interactions between hydrides and mesoporous supports by quantum chemical calculations and molecular dynamics simulations

O2: Preparation by mechanochemistry and complex characterization (structural, compositional, morphological and kinetics and thermodynamics of hydrogen absorption/desorption) of Li-Si-N-H amide/hydride composites.

O3: Preparation by mechanochemistry and complex characterization (structural, compositional, morphological and kinetics and thermodynamics of hydrogen absorption/desorption) of Li-Si-N-H amide/hydride composites of Li-Mg-Si-B-H composites  and Li, Ca, Mg modified boranates

O4: Synthesis of boranates impregnated into mesoporous supports by physical-chemical methods and complex investigations (XRD, SEM-EDAX, FTIR, microporosity -BET) and of hydrogen absorption/desorption kinetics and thermodynamics

O5: Design and building a demonstrative hydride tank for vehicular applications based on the hydrogen storage material with best properties obtained during project implementation

O6: Dissemination of the results through ISI publications and communications at international conferences and patenting the results for the hydrogen storage material with best properties obtained during project implementation